2 1/3 cups all-purpose flour
2 cups granulated sugar
1 teaspoon baking soda
1 cup Coca-Cola
2/3 cup butter or margarine
2 tablespoons unsweetened cocoa powder
2 eggs
1/2 cup buttermilk
2 teaspoons vanilla extract
1 1/2 cups mini marshmallows

Stir flour, sugar and baking soda, then set aside.

Bring Coca-Cola, butter and cocoa powder to a boil over medium heat. Add hot mixture to flour mixture. Stir just until combined. Add remaining ingredients, except marshmallows. Stir until combined. Gently stir in marshmallows. They will float to the top. Pour into a greased and floured 13 x 9-inch pan. Bake for 30 minutes at 350 degrees F.

Transfer cake to a wire rack. Immediately spread Cocoa Topping over cake. Thoroughly cool cake on rack.

Cocoa Topping
1/2 cup butter
1/4 cup unsweetened cocoa powder
1/4 cup Coca-Cola
2 1/2 cups sifted confectioners sugar
1 teaspoon vanilla extract
1 cup chopped nuts

Bring butter, cocoa powder and Coca-Cola to boiling. Add remaining ingredients.