4
Start with a layer of biscuits, sprinkle over a little dark chocolate and a dusting of cocoa. Spread a layer of the mascarpone mixture all over. Arrange 8 more sponge biscuits on top, more chocolate and cocoa, then another layer of mascarpone and another layer of biscuits, then the last of the chocolate and some more cocoa. Finish with a mascarpone layer and sift on the remaining cocoa powder