Coffee and chocolate opera cakes

Melt the small butter portion for the sponge and cool until lukewarm. Heat the oven to 200 °C. Separate 3 eggs, reserving their whites for the sponge and 2 yolks for the cream. Whisk 3 whole eggs with the almonds and icing sugar until foamy. Fold in 20 g warm melted butter. Whisk the reserved whites to peaks with 15 g sugar. Gently fold in this meringue, then the sifted flour. Spread thinly on a lined 30 × 40 cm tray. Bake for about 10 minutes until pale golden and springy. Cool for about 20 minutes.

Let the butter for the cream soften. Heat the small amount of water for dissolving the coffee. Dissolve 1 tsp instant coffee in 5 ml hot water. Cook 140 g sugar with 50 ml water to 120 °C. Whisk the remaining 2 whole eggs with the reserved yolks. Slowly pour in the hot syrup while whisking, keeping it clear of the whisk. Beat until fully cool. Gradually beat in 250 g very soft butter, then the cold dissolved coffee, until smooth.

Chop the chocolate. Bring the cream to a simmer and pour over 150 g chocolate. Stir from the centre outwards, then mix in 30 g butter. Cool until spreadable and able to hold its shape. In another pan, heat 150 ml water with 2 tsp instant coffee. Add the syrup’s reserved 200 ml water and 50 g sugar. Bring to the boil and cool.

Cut the cold sponge into rectangles to fit the individual frames. Put a sponge layer in each and brush with cold syrup. Spread on ganache, add another soaked sponge layer and then buttercream. Add another soaked sponge, more ganache and the final soaked sponge layer. Keep the fillings level. Chill for about 30 minutes to firm before glazing.

Gently melt the reserved 200 g chocolate with the glazing 100 g butter over a water bath. Stir and cool until fluid but no longer hot. Spread a thin layer over the cold cakes. Chill for at least 60 minutes until firm, then carefully remove the frames.