Opera Cake Recipe

Prep and whisk whole eggs and sugar

Preheat oven to 220°C (425°F). Line two baking sheets (half-sheet size) with parchment paper. In a large bowl, whisk together the whole eggs (6) and 100 g granulated sugar until the mixture is thick, pale, and ribbons fall slowly from the whisk (about 5–7 minutes by hand or 3–4 minutes with a stand mixer on medium-high).

Whip egg whites

In a separate clean bowl, whisk the 3 egg whites with 15 g sugar to medium-stiff peaks. Do not overbeat; peaks should hold but still be slightly glossy.

Fold dry ingredients and butter

Gently fold the almond flour (100 g) and all-purpose flour (30 g) into the whipped whole eggs in two additions, using a spatula to maintain volume. Fold in a pinch of salt and vanilla extract (1 tsp). Then fold in about one-third of the whipped egg whites to loosen the batter, followed by the remaining whites until just combined. Finally fold in the melted, cooled butter (40 g) quickly and gently until incorporated, keeping as much air as possible.

Bake

Spread the batter thinly and evenly (about 5 mm / 1/4 in thick) on the prepared parchment-lined baking sheets using an offset spatula. Tap sheets gently to remove large air pockets. Bake in the preheated oven for 5–7 minutes, until the sponge is golden and springs back lightly. Remove from oven and let cool on the sheet for 2 minutes, then transfer parchment with sponge to a rack to cool completely.

Trim

Once cooled, trim the edges and cut the sponge into 3 equal rectangles sized to fit your cake frame or a 23 x 33 cm (9 x 13 in) pan. If sponge has domed, level the top so layers stack evenly. You need three baked sheets/rectangles to assemble a traditional Opera cake (you can bake in batches if your oven/baking sheet size differs).

Combine 120 ml strong espresso and 50 g sugar in a small saucepan over medium heat. Stir until the sugar dissolves and the mixture is just simmering. Remove from heat and stir in 30 ml coffee liqueur if using. Cool to room temperature before brushing on the sponge layers.

Dissolve espresso

Dissolve 8 g instant espresso powder in 15 ml hot water and set aside to cool slightly.

Make sugar syrup

In a small saucepan, combine 100 g granulated sugar and 30 ml water. Bring to a boil and cook until the syrup reaches 115°C (239°F) on a candy thermometer (soft-ball approaching firm-ball for French buttercream).

Whisk yolks and temper

While the syrup heats, place 4 egg yolks in the bowl of a stand mixer and whisk lightly. When the syrup reaches 115°C, remove it from heat and, with the mixer on medium speed, slowly pour the hot syrup down the side of the whisking yolks in a thin stream to temper them. Continue whisking the mixture until it has cooled to near room temperature and is thick and glossy (several minutes).

Finish buttercream

With the mixer on low, add the softened butter (220 g) piece by piece, ensuring each addition is incorporated before adding the next. Once all butter is in, add the dissolved espresso mixture and a pinch of salt. Increase speed to medium-high and whip until the buttercream is smooth, silky, and spreadable. If the buttercream breaks or looks curdled, continue whipping; if it is too loose, chill briefly and rewhip.

Place the chopped dark chocolate (220 g) in a heatproof bowl. Heat the heavy cream (200 ml) just to a simmer (do not boil). Pour the hot cream over the chocolate and let sit for 1–2 minutes, then gently stir until smooth and glossy. Stir in 20 g butter for extra shine if desired. Cool until the ganache is spreadable but still pourable (lukewarm).

Layer 1: base sponge

Place the first trimmed jaconde rectangle on a flat working surface or in a cake frame (23 x 33 cm). Using a pastry brush, evenly brush the cake with about one-third of the coffee syrup (reserve the rest).

Layer 2: coffee buttercream

Spread about one-third of the coffee buttercream evenly over the moistened sponge to a thin layer (about 3–4 mm). Smooth the surface with an offset spatula.

Layer 3: second sponge

Place the second sponge rectangle on top, press lightly to adhere, and brush with more coffee syrup. Spread a thin layer of softened unsalted butter (20 g) if desired to help the next layer of ganache adhere, then spread about half of the ganache (cooled to spreadable) in a thin layer (3–4 mm).

Layer 4: coffee buttercream

Top with the third sponge layer, brush with remaining coffee syrup as needed. Spread another third of the coffee buttercream evenly across the top (same thickness).

Chill for stability

Place the assembled cake in the refrigerator for 20–30 minutes to firm slightly, which makes glazing and trimming easier.

Top ganache glaze

Once chilled, pour or spread the remaining ganache over the top of the cake in an even thin layer. Smooth with an offset spatula, ensuring straight edges. If desired, warm 40 g melted dark chocolate and pour a thin strip across the top for the classic shiny band; smooth quickly before it sets.

Final chill and trim

Chill the glazed cake for at least 1 hour to set. Before serving, remove from refrigerator and trim the edges with a hot knife for clean slices. Cut into portions (traditional Opera slices are narrow bars) and serve at cool room temperature.