Baking School In-Depth: Opera Cake


We’re kicking off this month’s lesson with a French classic: opera cake! A coffee- and chocolate-layered delight, the origins are uncertain. It is possible Louis Clichy created the first opera cake, a signature gâteau in his Paris shop. At the same time, Dalloyau, a pastry shop, sold a similar cake to honor the Paris Opera. To this day, the opera cake is a beloved classic with tender layers of almond sponge cake that are soaked in a rich coffee syrup. A bold Espresso French Buttercream and decadent chocolate ganache accompany the layers of cake, creating an unbeatable coffee-and-chocolate pairing. Covered in a stunning Chocolate Glaze, this dessert can’t help but be the star of the show! Don’t let the layers fool you—our lesson makes the baking process easy and straightforward with a step-by-step guide on how to create the perfect opera cake!

Click here to download a printable PDF of this lesson, or keep scrolling to view our digital lesson. And be sure to join us for Baking School with Williams Sonoma on Monday, February 13, 2023, at 5 p.m. PT. Brian Hart Hoffman, Brooke Bell, and Laura Crandall to make this lovely layered cake. Grab your Valentine and bake with us!

Ingredient Breakdown

Excellent recipes require wonderful ingredients. Here’s how our recipe’s ingredients contribute to making the very best opera cake.

BLANCHED ALMOND FLOUR: Almond flour is finely ground skinless blanched almonds. For this opera cake, almond flour is a wonderful addition as it creates a delicate, light, and airy sponge.

CONFECTIONERS’ SUGAR: Confectioners’ sugar is simply granulated white sugar that’s been ground to a fine powder. A bit of cornstarch is added to act as an anti-caking agent and brings a melt-in-your-mouth sweetness to this cake. Unlike granulated sugar, confectioners’ sugar dissolves quickly, easily, with an exceptionally smooth texture, making it perfect for the sponge cake.

CREAM OF TARTAR: Cream of tartar aids in stabilizing the whipped egg whites in the batter and helping them hold their volume.

UNBLEACHED CAKE FLOUR: Because it’s made from a soft wheat, unbleached cake flour makes a more delicate sponge than all-purpose flour, but with a protein content of 5% to 8%, it still provides enough structure for our cake.

UNSALTED BUTTER: As the name implies in our Espresso French Buttercream, butter is the main ingredient in this decadent frosting. An unsalted European-style butter, which has a higher fat content than other butters, creates a dreamy frosting that can easily be spread onto the sponge cake. We use unsalted butter since the salt content can vary across brands of butter, which lets us control the amount of salt used in this recipe.

BITTERSWEET CHOCOLATE: The high cacao content of bittersweet chocolate makes for a deep and less sweet flavor than milk chocolate, though sweeter than dark chocolate. Our recipe utilizes bittersweet chocolate in the ganache and glaze, creating the perfect chocolaty balance between the layers.

INSTANT ESPRESSO: Using instant espresso in both the buttercream and the Coffee Syrup enriches the chocolate flavor in the layers.

EGGS: Acting as an aid in leavening and adding moisture to the sponge cake, whole eggs and egg whites are used in our recipe to create stunning lift and sumptuousness in the cake.

VANILLA EXTRACT: Using vanilla extract in the sponge cake complements both the chocolate and coffee notes in the recipe.

WATER: Think of water as a connector of flavors in this cake. It brings the granulated sugar, espresso, and cognac together, creating an intense elixir to drizzle onto the chocolate sponge that ensures it tastes amazing and stays moist.

Tool Tête-à-Tête

We recommend this set of tools for our technique

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STAND MIXER: As a beloved energy-and time-saver, a stand mixer will help beat egg whites for the sponge cake. (Pictured is the KitchenAid® Artisan Stand Mixer, 5-Qt.)

SAUCEPAN: To make both the Coffee Syrup and the Espresso French Buttercream, you need a small stainless steel saucepan that heats evenly, with accurate temperature control and no hint of hot spots. (Pictured is the All-Clad d5 Stainless-Steel Saucepan.)

THERMOMETER: An instant-read thermometer will help give you confidence as you make the Espresso French Buttercream. As soon as the thermometer registers 240°F (116°C), the sugar syrup is ready to take off the heat and pour into the whipped egg yolks! (Pictured is the OXO Thermocouple Thermometer.)

OFFSET SPATULA: AOffset spatulas help you achieve a smooth top when making the sponge batter, spreading out the buttercream, ganache, and evenly coating the cake in the chocolate glaze. The larger one will help spread the sponge batter in just a few strokes, and the smaller one gives more control when finishing the layers. (Pictured is the Williams Sonoma Olivewood Offset Icing Spatula.)

HAND MIXER: For our Espresso French Buttercream, a hand mixer allows for power and speed but also more control when whipping air into egg yolks that might not have enough volume for a stand mixer to effectively reach and mix. (Pictured is the Breville Handy Mix Scraper 9-Speed Hand Mixer.)

SQUEEZE BOTTLE OR PASTRY BRUSH: This is essential for gently and evenly saturating the Coffee Syrup onto the delicate sponge cake. You can use a pastry brush if you don’t have a squeeze bottle. We recommend a brush with bristles instead of silicone for their flexibility and sturdiness. (Pictured is the OXO Chef’s Squeeze Bottle.)

PIPING TIP: Using an extra-large ribbon piping tip when piping the Espresso French Buttercream will make it easier to get an even layer of buttercream onto the sponge cake. (Pictured is the Ateco #898, part of the Ateco Pastry Tip Set.)

OPERA TORTE (GÂTEAU OPÉRA)

Opera cake is a decadent treat perfect for coffee-and-chocolate lovers, and it is worthy of any and every special occasion. This cake is comprised of layers of soft almond sponge cake, Coffee Syrup, chocolate ganache, and smooth coffee buttercream. Then, everything gets coated in an elegant Chocolate Glaze for its grand finale.

Opera Torte
 
Makes 6 servings
Ingredients
  • ¾ cup (72 grams) blanched almond flour
  • ½ cup (60 grams) confectioners’ sugar
  • 2 large eggs (100 grams)
  • 3 large egg whites (90 grams)
  • ¼ teaspoon cream of tartar
  • ¼ cup (50 grams) granulated sugar
  • 2½ tablespoons (20 grams) unbleached cake flour
  • 1 tablespoon (14 grams) unsalted butter, melted and cooled slightly
  • 1 teaspoon (4 grams) vanilla extract
  • 2 ounces (57 grams) 60% cacao bittersweet chocolate, chopped
  • Coffee Syrup (recipe follows)
  • Espresso French Buttercream (recipe follows)
  • Ganache (recipe follows) Chocolate Glaze (recipe follows)
Instructions
  1. Preheat oven to 400°F (200°C). Line a 17¼x12¼-inch rimmed baking sheet with parchment paper, letting excess extend over sides of pan.
  2. In a medium heatproof bowl, sift together almond flour and confectioners’ sugar. Add eggs, one at a time, whisking until well combined after each addition. Place bowl over a saucepan of simmering water; cook, whisking frequently, until an instant-read thermometer registers 95°F (35°C) to 105°F (41°C). Remove from heat, and whisk by hand until light and ribbon- consistency. (Alternatively, beat with a hand mixer at medium-high speed until light and ribbon-consistency.)
  3. In the bowl of a stand mixer fitted with the whisk attachment, beat egg whites and cream of tartar at medium speed until foamy. With mixer on medium speed, add granulated sugar in a slow, steady stream; increase mixer speed to medium-high, and beat until medium-stiff peaks form.
  4. Add almond flour mixture to egg white mixture, and very gently fold until almost combined. (Mixture should look streaky.) Sift cake flour over egg mixture, and gently fold until just combined. Transfer about 1 cup (75 grams) batter to a small bowl, and fold in melted butter and vanilla. Return mixture to large bowl, and fold until just combined. Pour large dollops across prepared pan, and gently spread into an even layer using as few strokes as possible.
  5. Bake until golden and firm to the touch, 8 to 9 minutes. Let cool in pan for 10 minutes. Using excess parchment as handles, remove from pan, and let cool completely on parchment on a wire rack.
  6. Move cake to a cutting board, and trim edges to create a 15×10½-inch rectangle. Discard edges. Cut into 3 (10½x5-inch) rectangles. Peel off parchment paper, and discard parchment. (Do not start soaking cake layers or assembling cake until syrup, buttercream, and ganache recipes are prepared and ready to be used.)
  7. In a small microwave-safe bowl, heat chocolate on high for 30 seconds; stir chocolate. Heat on high in 15-second intervals, stirring between each, just until chocolate is melted.
  8. Place 1 cake layer on a medium cutting board. Spread melted chocolate into an even layer on top of rectangle, being careful not to push it off cake onto cutting board. Refrigerate until firm, 5 to 10 minutes.
  9. Turn cake layer so chocolate is on bottom. Place Coffee Syrup in a squeeze bottle, and soak cake layer with syrup. (If you do not have a squeeze bottle, use a pastry brush to soak cake layer.) Place half of Espresso French Buttercream (about 1 cup or 200 grams) into a pastry bag fitted with an extra-large ribbon piping tip (Ateco #898). (This is to make it easier to get an even layer of buttercream. If you do not have a ribbon tip, you can dollop and spread buttercream into an even layer.)
  10. With flat side of piping tip facing up, pipe an even layer of buttercream on top of soaked cake layer; using a small offset spatula, smooth any lines. Place remaining Espresso French Buttercream in pastry bag, and set aside. Place second cake layer on top of buttercream layer, making sure it is even with bottom, and soak with Coffee Syrup. Dollop Ganache on top, and spread into an even layer. Top with remaining cake layer, and soak with Coffee Syrup. Pipe remaining buttercream on top, and smooth flat. Place a piece of parchment paper on top of buttercream. Refrigerate until firm, about 1 hour, or freeze until firm, about 30 minutes.
  11. Discard parchment. Place 2 tablespoons (30 grams) Chocolate Glaze into a parchment piping bag. (See step 5 of The Assemblage.) Quickly pour remaining Chocolate Glaze over cold buttercream, tapping and lifting cutting board to help it settle and smooth out. (It is OK if some drips down the sides.) Let stand until set, 5 to 7 minutes. Cut a very small opening in tip of parchment piping bag, and pipe “Opera” onto cake (and designs, if desired). Let stand until set, 5 to 7 minutes.
  12. Using a hot dry knife, trim edges, cleaning knife between cuts. Cut into 6 slices. Serve immediately. (If not serving right away, cover and refrigerate for up to 5 days until ready to serve and then trim and slice. Let stand at room temperature to soften buttercream.)
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Coffee Syrup
 
Makes about ¾ cup
Ingredients
  • ½ cup (100 grams) granulated sugar
  • ½ cup (120 grams) water
  • 1 teaspoon (1 gram) instant espresso
  • 2 tablespoons (30 grams) cognac
Instructions
  1. In a small saucepan, heat sugar and ½ cup (120 grams) water over medium heat, stirring constantly, until sugar dissolves. Stir in espresso. Remove from heat, and stir in cognac. Let cool completely before using.
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Espresso French Buttercream
 
Makes about 2 cups
Ingredients
  • 3 large egg yolks (56 grams), room temperature
  • ¾ cup (150 grams) granulated sugar
  • 3 tablespoons (45 grams) plus 1¾ teaspoon (9 grams) water, divided, plus more for brushing
  • ¾ cup plus 2 tablespoons (196 grams) unsalted butter, softened
  • 2½ teaspoons (2.5 grams) instant espresso
  • ¼ teaspoon kosher salt
Instructions
  1. In a medium heatproof bowl, beat egg yolks with a hand mixer fitted with the beater attachments at medium-high speed until pale yellow and slightly thickened, 3 to 4 minutes.
  2. In a small saucepan, stir together sugar and 3 tablespoons (45 grams) water over medium heat until sugar dissolves. Using a pastry brush dipped in water, brush sides of pan to prevent sugar granules from crystallizing. Increase heat to high, and bring to a boil. (Do not stir.) Cook until an instant-read thermometer registers 240°F (116°C).
  3. With mixer on low speed, slowly pour hot sugar syrup into egg yolk mixture in a slow, steady stream, being careful not to hit sides of bowl or mixer attachments; scrape sides of bowl. Increase mixer speed to high, and beat until bottom of bowl feels cool to the touch and mixture is very thick and very pale yellow, 4 to 5 minutes. Add butter, 1 tablespoon (14 grams) at a time, beating at medium speed until combined after each addition. (Mixture will look broken at times, but keep beating and it will come back together.)
  4. In a small bowl, stir together espresso and remaining 1¾ teaspoons (9 grams) water. Add espresso mixture and salt to buttercream, and beat at low speed until combined, stopping to scrape sides of bowl. Use immediately.
Notes
If you feel like your buttercream is too soft, which can happen if the butter is too warm or your egg mixture was not cool enough, refrigerate for 15 to 30 minutes, or place bowl over ice, stirring occasionally, and the buttercream will thicken nicely.
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Ganache
 
Makes about ⅔ cup
Ingredients
  • 4 ounces (113 grams) 60% cacao bittersweet chocolate, finely chopped
  • ½ cup (120 grams) warm heavy whipping cream
Instructions
  1. In the top of a double boiler, place chocolate. Heat, without stirring, over simmering water until almost melted. Gently stir until smooth. Remove from heat. Add warm cream, and starting in center of bowl, slowly stir with a rubber spatula until well combined. (Ganache will thicken as
  2. it cools.) Let stand until a spreadable consistency, about 15 minutes. (You can place in the refrigerator to help thicken faster; however, keep an eye on it so it doesn’t get too thick and hard to work with.)
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Chocolate Glaze
 
Makes about ⅔ cup
Ingredients
  • 5 ounces (142 grams) 60% cacao bittersweet chocolate, finely chopped
  • 4 teaspoons (20 grams) neutral oil
Instructions
  1. In the top of a double boiler, place chocolate. Heat, without stirring, over simmering water until almost melted. Gently stir until smooth. Remove from heat. Stir in oil. Let cool for 5 minutes before using.
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Embracing the Joconde

The foundation of this cake is the almond joconde sponge, a classic French pastry element. It’s nutty and rich but still as light as a sponge cake should be, creating the perfect base for our opera cake.    

1. Preheat oven to 400°F (200°C). Line a 17¼x12¼-inch rimmed baking sheet with parchment paper, letting excess extend over sides of pan.       

    

 

2. In a medium heatproof bowl, sift together almond flour and confectioners’ Add eggs, one at a time, whisking until well combined after each addition. Place over a saucepan of simmering water; cook, whisking frequently, until an instant-read thermometer registers 95°F (35°C) to 105°F (41°C). Remove from heat, and whisk by hand until light and ribbon-consistency. (Alternatively, beat with a hand mixer at medium-high speed until light and ribbon- consistency.) The mixture should fall off the whisk in ribbons. For this step of the recipe, confectioners’ sugar will dissolve more quickly and easily than granulated sugar. You can use a spoon or whisk to help push the almond flour and sugar through the sieve.

    

 

3. In the bowl of a stand mixer fitted with the whisk attachment, beat egg whites and cream of tartar at medium speed until foamy. With mixer on medium speed, add sugar in a slow, steady stream; increase mixer speed to medium-high, and beat until medium-stiff peaks form. Granulated sugar aids in the stabilization of the egg whites, but make sure you slowly add the sugar in a steady stream, which will ensure you don’t deflate all the lovely air you whipped into the egg whites; it also helps make sure the sugar dissolves so you don’t have textured meringue at the end.

 

4. Add almond flour mixture to egg white mixture, and very gently fold until almost combined. (Mixture should look streaky.) Sift cake flour over egg mixture, and gently fold until just combined. Transfer about 1 cup (75 grams) batter to a small bowl, and fold in melted butter and vanilla. Return mixture to large bowl, and fold until just combined. Lightly folding the eggs in at this step is key to a beautiful, airy sponge. Don’t be tempted to get every bit of white and yolk folded together! Most importantly, make sure you don’t overwork the batter. If you knock the air out of the eggs, the sponge won’t rise properly.

 

 

5. Pour large dollops across prepared pan, and gently spread into an even layer using as few strokes as possible. Pouring the batter in dollops will help you in spreading the batter, but you also want to make sure you aren’t deflating the batter as you spread it into the prepared pan.

6. Bake until golden and firm to the touch, 8 to 9 minutes. Let cool in pan for 10 minutes. Run a knife over any edges that may have clung to pan. Using excess parchment as handles, remove from pan, and let cool completely on parchment on a wire rack. Using the excess parchment as a “sling” will help you transfer this delicate sponge with grace and ease!

 

7. Move cake to a cutting board, and trim edges to create a 15×10½-inch Discard edges. Cut into 3 (10½x5- inch) rectangles. Peel off parchment paper, and discard parchment. (Do not start assembling cake until syrup, buttercream and ganache recipes are prepared and ready to be used).

A Lovely Elixir

Espresso and cognac complement the flavor of chocolate as this syrup is brushed on the sponge cake layers

   

 

1. In a small saucepan, heat sugar and ½ cup (120 grams) water over medium heat, stirring constantly, until sugar dissolves. Stir in espresso powder. Remove from heat, and stir in cognac. Let cool completely before using. Using a squeeze bottle for the Coffee Syrup will help you saturate the cake evenly with coffee and cognac, which are flavors that perfectly complement the chocolate and almond in this splendid cake.

Billowing Buttercream

Lofty and luscious, our Espresso French Buttercream is beautifully balanced between the sweetness of the granulated sugar, the inherent depth and bitterness of espresso, and the richness of the unsalted butter.

1. In a medium heatproof bowl, beat egg yolks with a hand mixer fitted with the beater attachments at medium-high speed until pale yellow and slightly thickened, 3 to 4. Be patient during this step. You want to make sure the egg yolks have time to properly aerate.

 

2. In a small saucepan, stir together sugar and 3 tablespoons (45 grams) water over medium heat until sugar dissolves. Using a pastry brush dipped in water, brush sides of pan to prevent sugar granules from crystallizing. Increase heat to high, and bring to a boil. (Do not stir.) Cook until an instant-read thermometer registers 240°F (116°C). If the sugar granules that collect on the sides of the saucepan aren’t brushed down, the sugar can harden and crystallize.

 

 

3. With mixer on low speed, slowly pour hot sugar syrup into egg yolk mixture in a slow, steady stream, being careful not to hit sides of bowl or beater attachments; scrape sides of bowl. Increase mixer speed to high, and beat until bottom of bowl feels cool to the touch and mixture is very thick and very pale yellow, 4 to 5 minutes. Add butter, 1 tablespoon (14 grams) at a time, beating at medium speed until combined after each addition. (Mixture will look broken at times, but keep beating and it will come back together.) As you are adding the butter to the egg yolk and sugar mixture, the butter should give just a slight resistance to the pressure of your fingers. If your butter is too cold, it can cause your buttercream to break. If you feel like your buttercream is too soft, which can happen if the butter is too warm or your egg mixture was not cool enough, refrigerate for 15 to 30 minutes, or place bowl over ice, stirring occasionally, and the buttercream will thicken nicely.

 

 

4. In a small bowl, stir together espresso and remaining 1¾ teaspoons (9 grams) Add espresso mixture and salt to buttercream, and beat at low speed until combined, stopping to scrape sides of bowl. Use immediately.

Going Gaga Over Ganache

Simple yet decadent, the ganache is the center layer, and its sweetness pairs beautifully with the bitter coffee notes

1. In the top of a double boiler, place chocolate. Heat, without stirring, over simmering water until almost melted. Gently stir until Remove from heat. Add warm cream, and starting in center of bowl, slowly stir with a rubber spatula until well combined. (Ganache will thicken as it cools.) Let stand until a spreadable consistency, about 15 minutes. (You can place in the refrigerator to help thicken faster; however, keep an eye on it so it doesn’t get too thick and hard to work with.)

Glaze Up

Straightforward and super smooth, this simple glaze made of bittersweet chocolate and neutral oil gives the cake a polished, elegant finish

 

1. In the top of a double boiler, place chocolate. Heat, without stirring, over simmering water until almost melted. Gently stir until smooth. Remove from heat. Stir in oil. Let cool for 5 minutes before using. Adding oil to the melted chocolate re-emulsifies the chocolate and helps thin it out, creating a smooth, glossy finish that’s easy to work with.

The Assemblage

Now that all the elements of this cake are ready, it’s time for the finale

1. In a small microwave-safe bowl, heat chocolate on high for 30 seconds; stir chocolate. Heat on high in 15-second intervals, stirring between each, just until chocolate is melted. Tempering the chocolate in the microwave will allow it to reharden and stay that way at room temperature. It acts as both a base for the cake and support for the cake-soaked layer.

2. Place 1 cake layer on a medium cutting board. Spread melted chocolate into an even layer on top of rectangle, being careful not to push it off cake onto cutting board. Refrigerate until firm, 5 to 10 minutes. Using an offset spatula will help spread the melted chocolate across the top layer of the cake effortlessly!

 

3. Turn cake layer so chocolate is on bottom. Place Coffee Syrup in a squeeze bottle, and soak cake layer with syrup. (If you do not have a squeeze bottle, use a pastry brush to soak cake layer.) Place half of Espresso French Buttercream (about 1 cup or 200 grams) into a pastry bag fitted with an extra-large ribbon piping tip (Ateco #898). (This is to make it easier to get an even layer of buttercream. If you do not have a ribbon tip, you can dollop and spread icing into an even layer.) With the tempered base, you can move the assembled cake around easily with a large offset spatula.

4. With flat side of piping tip facing up, pipe an even layer of buttercream on top of soaked cake layer; using a small offset spatula, smooth any lines. Place remaining Espresso French Buttercream in pastry bag, and set aside. Place second cake layer on top of buttercream layer, making sure it is even with bottom, and soak with Coffee Syrup. Dollop Ganache on top, and spread into an even layer. Top with remaining cake layer, and soak with Coffee Syrup. Pipe remaining buttercream on top, and smooth flat. Place a piece of parchment paper on top of buttercream. Refrigerate until firm, about 1 hour, or freeze until firm, about 30 minutes.

    5. Discard parchment. Place 2 tablespoons (30 grams) Chocolate Glaze into a parchment piping bag. (See note below.) Quickly pour remaining Chocolate Glaze over cold buttercream, tapping and lifting cutting board to help it settle and smooth out. (It is OK if some drips down the sides.) Let stand until set, 5 to 7 minutes. Cut a very small opening in tip of parchment piping bag, and pipe “Opera” onto cake (and designs, if desired). Let stand until set, 5 to 7 minutes. Be confident yet quick when spreading the glaze, as it will set speedily once it hits the cold buttercream. You should not have to spread the glaze if you move the board to distribute the glaze. This way, you won’t have streaks, just a perfectly smooth surface. It is important for the glaze to be warm but not too hot so that the buttercream doesn’t melt.

Note: To make the parchment piping bag: Fold the parchment in half diagonally, pressing firmly along the crease. Rotate the parchment to align the crease with the edge of your work surface. Cut the parchment along the seam with a knife, creating two right triangles. Grab the far corner between your thumb and index finger and then roll the parchment around itself. Drag the paper until it forms a tight cone. While holding the cone in place with your right hand, lift up the loose parchment so you can slide your thumb under the cone to pinch it in place. With the cone secured between your right thumb and index finger, use your left hand to wrap the extra parchment around the cone until you have nothing left but a small flap that can be tucked into the body of the cone itself.

6. Using a hot dry knife, trim edges, cleaning knife between cuts. Cut into 6 slices. Serve immediately. (If not serving right away, cover and refrigerate until ready to serve and then trim and Let stand at room temperature to soften buttercream.) Simply heat the knife under hot water and dry it off in between slicing to get perfect, smooth slices of cake.



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