4 cups heavy cream, divided
8 oz. mascarpone cheese
1 1/4 c powdered sugar, divided
1/4 c Cream de Cacao (chocolate liqueur) optional
3 tablespoons unsweetened coco powder
1 teaspoon vanilla extract
2 boxes (14 oz each) chocolate graham crackers (you will not need them all)
1 1/2 c heavy cream
1/2 c powdered sugar
shaved semisweet chocolate or crushed choc graham crackers for garnish
Combine 3/4 cup powdered sugar and coco powder in a small bowl, mix well, set aside. In the bowl of an electric mixer with a whisk attachment add room temperature Mascarpone and 1/2 cup of heavy cream, mix until cheese is smooth. Add an additional 2 cups heavy cream, the coco/sugar mixture, the chocolate liqueur and the vanilla, beat on high speed until thick and fluffy.
Start assembling the cake: arrange chocolate graham crackers flat in the bottom of an 8 or 10 inch springform pan. Cover the bottom as much as possible, placing the crackers as close and flat and even as possible will yield the best looking cake when it is sliced, you will need to break a few crackers. Spread a thin layer, about a fifth of the chocolate cream mixture evenly over the crackers. Add another layer of chocolate graham crackers, close and flat and even. Layer again with one fifth of the chocolate cream. Continue with three more layers, ending with a chocolate cream level.
In a mixer bowl combine the final 1 1/2 cups of heavy cream and 1/2 cup of powdered sugar, beat until thick and fluffy. Spread whipped cream as the top layer of the cake, smoothing the top as flat and even as possible. Cover with plastic wrap and refrigerate12 to 24 hours.
Ready to serve: run a thin narrow knife around the outside of the cake and remove the side of the pan. Sprinkle the top with shaved semisweet chocolate or with crushed chocolate graham crackers. Serve cold.