- Whisk the egg yolks, caster sugar and brandy in a bowl over a saucepan of barely simmering water until mixture thickens. Take care not to let the bowl touch the water or the water get too hot, as the eggs can easily scramble.
- Add egg mixture to the mascarpone and mix until smooth. Beat the cream until softly whipped and fold into the egg mixture.
- Whisk the egg whites until they form soft peaks and gently fold into the egg yolks.
- Arrange a layer of the sponge finger biscuits over the base of a 2- litre bowl, pour over a little cooled coffee and spoon in egg mixture. Cover with biscuits, more coffee and cream and continue to layer until ingredients have been used. The number of layers will depend on bowl shape.
- Dust the top with cocoa and grated chocolate and refrigerate for at least 2 hours prior to serving - overnight if possible.