Whisk eggs and sugar together in a heat proof bowl over a pan of simmering water, but do not allow it to touch the water. Using a handheld electric mixer, beat for approximately 7 minutes or until mixture has tripled in volume and a candy thermometer inserted into it reads 160° F. Remove bowl from pan.
Beating constantly, add liqueur 1 Tbsp at a time. Continue beating for about 5 minutes or until mixture is cool.
When cool, beat in mascarpone until well blended. If using, stir in chocolate bits and/or fruit. Cover and refrigerate for 1 hour or until well chilled.
Combine water, brown sugar, espresso powder, and cocoa in a medium bowl. Stir until espresso powder and cocoa dissolve.
One at a time, completely dip biscuits into the espresso mixture, then put them in the bottom of a 13 x 9 x 2-inch glass baking dish to completely cover the bottom. If necessary, cut biscuits to fit.
Evenly spread one third of the mascarpone mixture over the biscuits. Continue dipping and layering, making 2 additional layers of biscuit and mascarpone, ending with a cheese layer.
Tightly cover with plastic wrap and refrigerate for at least 8 hours.
When ready to serve, sprinkle grated chocolate over the top. Cut into squares and serve cold.Makes 4 Source: