I may be making another wedding cake so I had to try it out. The results were yummy and awsome. Chocolate cake (see prior post on America's Test Kitchen classic chocolate cake), Mocha filling, a thin coating of buttercream, and then marshmallow fondant. Here are some recipies
Mocha Filling
2oz unsweetened chocolate
1 stick unsalted butter
6 tsp instant Coffee
1 Tbs water
3 cups (approx) powdered sugar
Beat the butter until fluffy. While that's beating, melt the chocolate in the microwave with a dot of crisco or vegtable oil.
Add the melted chocolate to the butter and beat well. Having the chocolate not ridiculously hot is desirable or the butter melts.
Combine the instant coffee and water into super-strength coffee extract in a small bowl. Mix well to ensure no coffee crystals are left and then add to the butter and chocolate.
Then add powdered sugar. I'm guessing around 3 cups. Less than in normal frosting. It will probably need to be chilled because undoubtedly you put the chocolate in while very hot and half the butter melted in a mess.
Marshmallow fondant
There's a whole website devoted to this. In summary.
1 lb package mini marshmallows
4 Tbs water
2 lbs powdered sugar
Heat the marshmallows and water in the microwave (around 2min) stopping often to stir until they are melted.
Add about 3/4 of the confectioners sugar and mix well.
Grease the counter and yourself (crisco, not butter). Heck, coat the entire kitchen with crisco while you're at it, this stuff sticks! knead in the rest of the sugar like it was bread dough. keep kneading until you get a smooth dough (about 5-8min) double wrap in plastic and put in a freezer bag in the fridge overnight.
use cornstarch to keep it from sticking when you roll it out.