Just take your favorite white cake recipe, torte into four layers, and soak with coffee mixed with Marsala or another booze of your choice. Make the mascarpone filling (NOT anything with cream cheese), fill the cake, and then dust each layer of filling with cocoa powder or chocolate shavings. Here is a recipe you can use for the cream filling:
http://www.epicurious.com/recipes/food/views/Tiramisu-107833
I personally wouldn't ice this in anything but whipped cream, to maintain the likeness to the original dessert. But I suppose if you wanted to ice it in buttercream and then cover in fondant, you could.
Edited by AnnieCahill - 1/25/13 at 7:19am