Cake: Heat oven to 350 degrees F. Grease and flour a 13 x 9-inch baking pan.
Combine dry ingredients in a bowl.
Heat butter, cocoa and Coca-Cola to boil and pour over the flour mixture. Mix
well. Add eggs, buttermilk, vanilla extract and marshmallows and blend. The batter
will be thin with marshmallows floating on top. Bake for 45 minutes.
Frosting: Boil first three ingredients. Remove from the heat and blend in the
sugar and vanilla extract. Spread on warm cake.