1 c. unsalted butter
1/2 c. miniature marshmallows
1/4 c. unsweetened cocoa
1 c. Coca-Cola
2 c. sugar
1 tsp. baking soda
2 eggs, lightly beaten
1/2 c. buttermilk

ICING:

6 oz. semi sweet chocolate, coarsely chopped
1/3 c. Coca-cola
1 c. plus 2 tbsp. unsalted butter, softened
3 egg yolks
2/3 c. confectioners' sugar

Heat oven to 350 degrees. To make the cake: combine butter and marshmallows in a medium saucepan over low heat. Cook, stirring occasionally until marshmallows melt. Stir in cocoa and Coca-Cola. Remove from heat. Sift in sugar, flour and baking soda together. Beat in chocolate - cola mixture. Add eggs and buttermilk. Beat until smooth. Pour into two 9 inch round cake pans. Bake cake until toothpick comes out clean.

To make icing: Place the chocolate and coca-cola in a small saucepan. Cook over low heat, stirring constantly, until smooth. Remove from heat; let cool. Refrigerate until cold. Beat the butter until light and fluffy. Beat in egg yolks, one at a time. Gradually add chocolate mixture. Beat in confectioners' sugar.