Opéra Cake

Dissolve instant coffee in hot water. Add 50 g granulated sugar and stir until dissolved. Set aside to cool.

Preheat oven to 200°C (400°F). Line a 30x40 cm (12x16 inch) baking sheet with parchment paper. In a bowl, whisk together almond flour, powdered sugar, and all-purpose flour. Add whole eggs one at a time, mixing well. In a clean bowl, beat egg whites until foamy, then gradually add 50 g granulated sugar and beat until stiff peaks form. Fold egg whites into almond mixture in three additions. Finally, fold in melted butter. Spread batter evenly onto prepared baking sheet. Bake for 10-12 minutes until lightly golden and springy. Let cool completely.

In a small saucepan, combine 150 g granulated sugar and water. Bring to a boil without stirring until it reaches 118°C (245°F) on a candy thermometer. Meanwhile, beat egg yolks in a stand mixer until thick and pale. With mixer running, slowly pour hot sugar syrup into yolks. Continue beating until bowl is cool to touch. Gradually add softened butter, beating until smooth. Add reserved coffee syrup (about 3 tablespoons) and beat to combine. Set aside.

Place chopped chocolate in a heatproof bowl. Heat cream until just simmering, then pour over chocolate. Let sit 1 minute, then stir until smooth. Let cool until thick but spreadable.

Melt chocolate and butter together over a double boiler or in short bursts in microwave. Stir until smooth. Keep warm.

Cut the cooled joconde sponge into 3 equal rectangles (about 10x12 inches each). Place one layer on a serving board. Brush generously with coffee syrup. Spread half of the coffee buttercream evenly over the sponge. Place second sponge layer on top, brush with syrup, then spread all the chocolate ganache. Top with third sponge layer, brush with syrup, and spread remaining coffee buttercream. Refrigerate for at least 1 hour to firm.

Pour the warm chocolate glaze over the chilled cake, using an offset spatula to spread it evenly over the top and let it drip down the sides. Tap the board gently to smooth. Refrigerate for 30 minutes to set the glaze.

Using a sharp knife dipped in hot water and wiped dry, slice the cake into neat rectangles. Serve at room temperature.