Opera Prima Recipe

Prepare oven and pan

Preheat oven to 180°C (350°F). Line a 23x33 cm (9x13 in) rimmed baking sheet with parchment paper leaving an overhang for easy removal.

Whip eggs and sugar

In a heatproof bowl set over a pot of barely simmering water (bain-marie), whisk the 5 whole eggs with 125 g sugar and a pinch of salt until warm to the touch (about 40°C / 104°F). Remove from heat and using a stand mixer or hand mixer, whip on high until tripled in volume and the ribbon stage is reached (pale, thick, and falls from the whisk leaving a trail). This takes about 6–8 minutes.

Fold in dry ingredients

Sift together 75 g flour and 25 g cocoa powder. Gently fold a third of the whipped eggs into the dry mix to loosen it, then carefully fold in the remaining egg mixture with a spatula using wide strokes to preserve volume.

Add butter and bake

Fold in 40 g melted butter and 1 tsp vanilla extract quickly but gently until just incorporated. Pour the batter evenly into the prepared sheet pan and smooth the top. Bake 10–12 minutes, or until the cake springs back lightly and a skewer comes out mostly clean. Do not overbake — it should remain pliable.

Cool and trim

Allow the sponge to cool in the pan for 5 minutes, then invert onto a clean kitchen towel or parchment and remove the baking paper. Trim the edges to make straight sides and cut the sheet into three equal rectangular layers (approximately 3 layers 23x11 cm each). If the top is domed, level it gently so layers stack evenly.

Combine 120 ml hot brewed espresso and 40 g sugar in a small saucepan. Heat just until the sugar dissolves, stirring, then remove from heat and stir in 15 ml coffee liqueur if using. Cool slightly; transfer to a shallow dish for brushing. Keep warm or at room temperature for assembly.

Cook yolks with sugar and coffee

In a heatproof bowl over a bain-marie, whisk together 4 egg yolks, 80 g sugar and 40 ml cooled strong espresso. Stir constantly until the mixture thickens slightly and reaches about 71°C (160°F) or becomes noticeably more viscous (this pasteurizes the yolks). Remove from heat.

Chill and whip

Transfer the yolk mixture to a clean bowl and cool to room temperature, then refrigerate until cold (about 20–30 minutes), occasionally stirring to prevent skin. Once chilled, beat the mixture with a paddle or whisk until smooth.

Incorporate butter

With the mixer on medium speed, add 220 g softened butter a few tablespoons at a time until fully incorporated and the buttercream is smooth and silky. Add 1 tsp vanilla and a pinch of salt, then taste and adjust coffee intensity with a little more espresso (a teaspoon at a time) if desired. Keep at cool room temperature; if it becomes too soft chill briefly and rewhip before assembly.

Make ganache

Place 200 g finely chopped dark chocolate in a heatproof bowl. Heat 200 ml heavy cream until it just begins to simmer (small bubbles on the edge), then pour over the chocolate. Let sit 1 minute, then gently stir until smooth. Add 20 g unsalted butter and stir until glossy and fully combined. Cool to a pourable but slightly thick consistency (about 30–40°C). If it becomes too firm, warm gently over a bain-marie.

Brush and layer

Place the first chocolate sponge layer on a serving board or tray. Using a pastry brush, saturate the sponge evenly with the coffee syrup (about 3–4 tablespoons). Spread approximately one-third of the coffee buttercream in an even layer over the soaked sponge (about 150–180 g). Place the second sponge layer on top, press gently to adhere. Repeat: brush with syrup and spread another third of the buttercream.

Final layer and crumb coat

Top with the third sponge layer, brush with syrup, then spread the remaining buttercream in a thin, even layer to the edges to create a smooth top. Use the reserved 20 g softened butter to help achieve a clean crumb-coat if needed.

Chill before glazing

Refrigerate the assembled cake for 20–30 minutes until the buttercream is firm but not rock hard. This prevents the ganache from sliding.

Glaze with ganache

Place the chilled cake on a rack over a tray to catch drips. Pour the slightly cooled, pourable ganache evenly over the top, using an offset spatula to encourage smooth coverage and clean edges. Allow excess to drip off, then smooth the sides quickly if desired. If needed, trim any drip spills once set.

Set and finish

Return the cake to the refrigerator for at least 1 hour to set fully. Before serving, let sit 10–15 minutes at room temperature for best texture. Optionally dust edges with cocoa powder or sprinkle chocolate shavings for decoration. Slice into neat rectangles using a hot, clean knife between cuts for clean edges.