Make coffee with percolator (machinetta) or use instant coffee. Add liquor to coffee.

Pour into dish large enough to dip biscuits

In a clean bowl mix egg yolks and caster sugar together till pale and slightly thick, add mascarpone and fold in until mixed through. Dip biscuits until they are infused with coffee but not soaked or mushy. When first layer is complete cover with mascarpone mixture and continue layering. Should get 3 layers out of this recipe. Sift cocoa powder on to the top of the layers. Cover with cling wrap and refrigerate overnight to allow flavours to soak through. 

Cut into desired serving sizes and serve. Buon appetito.