Slice your sponge cake into two even layers. Place the first layer on a serving plate.
Combine espresso with coffee liqueur, then lightly brush or drizzle over the first cake layer.
In a large bowl, whip heavy cream, sugar, and vanilla until soft peaks form. Gently fold in the mascarpone until smooth and creamy.
Spread half of the mascarpone cream over the first cake layer.
Add the second cake layer, drizzle lightly with coffee mixture, and spread the remaining cream on top.
Dust with cocoa powder and add chocolate shavings for a professional finish.
Chill in the refrigerator for at least 4 hours, ideally overnight, before slicing and serving.