Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a bowl, whisk eggs and powdered sugar until pale and fluffy.
Gently fold in almond flour and all-purpose flour until combined.
Add melted butter and mix until smooth.
Spread the batter evenly on the prepared baking sheet.
Bake for 15-20 minutes until lightly golden and springy to the touch.
Allow the sponge to cool completely, then cut into three equal rectangles.
Prepare the coffee buttercream by beating softened butter and powdered sugar together.
Add brewed coffee gradually and mix until fluffy.
For the ganache, heat heavy cream until just boiling, then pour over chopped chocolate and let sit for 5 minutes.
Stir until smooth, then let it cool slightly before assembling.
Layer the sponge, buttercream, and ganache, repeating for three layers.
Chill in the fridge for at least 2 hours before slicing and serving.