Opera Cake with Espresso Buttercream
Opera Cake
A polished French-style opera cake layered with almond sponge, espresso syrup, silky coffee buttercream, and dark chocolate ganache.
Opera cake is a compact showpiece built from very thin almond sponge, coffee syrup, coffee buttercream, and chocolate ganache. The finished cake is trimmed after chilling, so every slice shows crisp horizontal layers of pale sponge, dark chocolate, and espresso cream.
The recipe works best when treated as a sequence of small components rather than one intimidating project. Bake the sponge sheets first, then make the buttercream, ganache, and syrup before cutting the cakes into even rectangles for stacking.
A candy thermometer is useful for the buttercream because the hot sugar syrup gives the yolk-based frosting its glossy, stable texture. If the buttercream looks curdled while the butter is going in, keep beating; it usually becomes smooth once the mixture warms and emulsifies.
Plan to chill the assembled cake before trimming and serving. The rest firms the ganache and buttercream, makes the layers easier to cut cleanly, and improves the flavor as the espresso syrup settles into the almond sponge.
Nutrition (per serving)
Directions
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1
Heat the oven to 350°F. Line two 9 by 13-inch baking pans with parchment, then spray the parchment and exposed sides so the sticky sponge releases cleanly.
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2
Whip the egg whites on medium speed until foamy and opaque. Add the kosher salt and the 1 1/2 tablespoons sugar, then beat on high until the meringue is glossy and holds firm peaks.
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3
Transfer the meringue to a clean bowl. In the same mixer bowl, beat the 4 whole eggs with the remaining 3/4 cup sugar for 8 to 10 minutes, until thick, pale, and ribbony.
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4
Fold the all-purpose flour into the egg mixture, then fold in the almond flour in two additions. Gently fold in the meringue just until no large white streaks remain.
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5
Divide the batter between the prepared pans and smooth it thinly and evenly. Bake for 9 to 13 minutes, until the cakes are set and spring lightly when touched, then cool completely in the pans.
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6
For the buttercream, boil the water and 3/4 cup sugar without stirring until the syrup reaches 238°F. Beat the egg yolks for 2 minutes, then pour in the hot syrup in a slow stream while the mixer runs.
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7
Beat the yolk mixture with the 2 tablespoons cooled espresso until combined, then let it cool near room temperature. Add the softened butter a few pieces at a time, beat until silky, and finish with the fine salt.
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8
For the ganache, place the chopped chocolate in a bowl. Bring the cream just to a simmer, pour it over the chocolate, wait 1 minute, then whisk smooth and let it thicken to a spreadable consistency.
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9
For the syrup, stir the hot espresso with the 1/2 cup sugar until dissolved, then stir in the brandy. Cut each cooled sponge sheet into 3 equal rectangles, giving you 6 thin cake layers.
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10
Assemble in this order: sponge, espresso syrup, ganache, sponge, syrup, buttercream. Repeat twice more, ending with buttercream on top, then chill until firm.
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11
Spread the remaining ganache over the chilled top. Refrigerate for at least 2 hours or overnight, then trim the edges with a sharp serrated knife and serve in neat slices.
Ingredients
- Large Egg Whites:4
- Kosher Salt:1/2 teaspoon
- Granulated Sugar, divided for sponge:3/4 cup plus 1 1/2 tablespoons
- Large Eggs:4
- All-Purpose Flour:1/4 cup
- Almond Flour:1 1/3 cups
- Water:1/2 cup
- Granulated Sugar, for buttercream syrup:3/4 cup
- Large Egg Yolks:4
- Cooled Espresso, for buttercream:2 tablespoons
- Unsalted Butter, softened and cubed:1 cup
- Fine Salt, for buttercream:2 pinches
- Semisweet or Bittersweet Chocolate, finely chopped:8 ounces
- Heavy Cream:1 cup
- Hot Espresso, for syrup:10 tablespoons
- Granulated Sugar, for espresso syrup:1/2 cup
- Brandy or Cognac:3 tablespoons
- Nonstick Baking Spray:as needed
Tips & Notes
- Use decaf espresso if the cake will be served late in the day.
- If the buttercream separates after the butter is added, keep beating on medium-high speed until it smooths out.
- Replace the brandy with more espresso for an alcohol-free syrup.
- Chill the cake well before trimming; cold ganache and buttercream make the striped edges much cleaner.
- Hazelnut flour can replace almond flour for a deeper nut flavor.
