This glaze is the perfect topping for a chocolate or marble bundt cake. It's rich root beer flavor but chocolate like appearance will have people questioning "what's in this?". For even more root beer flavor try substituting root beer for the water in your cake. This will work whether you use a mix or make it from scratch.
Root Beer Icing
1 stick of butter
1/3 cup root beer (not diet)
1 box powdered sugar
Cut 1 stick of margarine into several pieces and melt in a medium saucepan with 1/3 cup root beer. Bring to a boil and add 1 box of powdered sugar. Mix well and pour over the cake once the cake has cooled for 3 to 5 minutes (but while both the cake and the icing are still warm).