Whisk egg white until stiff.
Mix egg yolk together with sugar until creamy.
Then mix in the mascarpone with the yolk and sugar.
Slowly add egg white and stir.
Add amaretto to the coffee and dip the sponge fingers in one by one and then place into a tin. Spoon the mascarpone/egg mixture on top and then add another layer of sponge fingers as well as the mascarpone mixture.
Sprinkle with cocoa powder and put in the fridge overnight.