Opera cake with coffee buttercream: mocha flavor and neat layers under chocolate glaze

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1. Beat the batter

   10 min

   Preheat the oven to 200 °C (400 °F) and line a 30 × 40 cm baking sheet with parchment paper. Beat the whole eggs with the almond flour and powdered sugar until thick and pale, about 5 minutes. Gently fold in the sifted all-purpose flour and melted butter.

2. Bake the sponge

   15 min

   Beat the egg whites with the granulated sugar until stiff, glossy peaks form, then gently fold them into the batter with a spatula. Spread the batter evenly on the prepared baking sheet and bake at 200 °C (400 °F) for 8–10 minutes, until golden. Turn the sponge out onto a clean sheet of parchment paper, peel off the baking parchment, and let cool.

3. Make the coffee syrup

   5 min

   Bring the water and sugar to a boil, remove from the heat, and stir in 2 tbsp instant coffee. Let cool.

4. Prepare the buttercream and filling

   15 min

   Beat the softened butter with the powdered sugar until fluffy, then mix in the coffee dissolved in 1 tbsp hot water. For the filling, heat the cream until nearly boiling, remove from the heat, add 100 g chocolate broken into pieces, and stir until melted. Let thicken.

5. Assemble the layers

   45 min

   Cut the sponge into 3 equal rectangles, each about 30 × 13 cm. Place the first rectangle on a serving tray, soak with syrup, and spread with half the coffee buttercream. Add the second rectangle, soak it with syrup, and spread with the chocolate filling. Top with the third rectangle, soak it with syrup, spread with the remaining buttercream, and refrigerate for 30 minutes.

6. Add the chocolate glaze

   10 min

   Melt the remaining chocolate with the oil in a bowl over simmering water, let cool slightly, and pour over the chilled cake. Spread it in one stroke for a smooth surface. If desired, reserve a spoonful of glaze and use it to write the word Opéra on top.

7. Chill until set

   3 hr

   Refrigerate the cake for at least 3 hours. Trim the edges and cut into slices with a sharp knife dipped in hot water and wiped dry. This will give the slices neat layers.

Tip: The cake keeps in the refrigerator for 3 days; take it out about 15 minutes before serving to let the buttercream soften slightly. Save the trimmed edges for tasting. Read more: How to adjust a recipe for your baking pan

This recipe was translated from the Slovak original: Opera rezy s kávovým krémom: chutia ako mocca a pod čokoládovou polevou držia rovné vrstvy