Coke Float Cupcakes

The feedback I got from Travis's friends was that the cupcake itself was not sweet enough and the frosting was too sweet.  I really like them, and so did the book club.  Feel free to tweak as necessary.  If I made them again though, I'd probably go a little heavier on the mini marshmallows because I think I was a little too stingy with them in this batch.  Coca-cola cake recipe courtesy of the Coca-Cola Company's website, adapted for cupcakes.  It made about 20 standard cupcakes but would probably also be nice as mini-cupcakes (decrease cooking time).  The icing is not the recommended one from the Coca-Cola website, but a variation of my own American Buttercream.  This recipe might also be tasty with root beer.

Cake:
2 cups sugar
2 cups all-purpose flour
1 1/2 cups small marshmallows
1/2 cup butter
1/2 cup vegetable oil
3 tablespoons cocoa
1 cup Coca-Cola®
1 teaspoon baking soda
1/2 cup buttermilk
2 eggs
1 teaspoon vanilla extract

Preheat oven to 350 degrees. In a bowl, sift sugar and flour. Add marsh- mallows. In saucepan, mix butter, oil, cocoa, and Coca-Cola. Bring to a boil and pour over dry ingredients; blend well. Dissolve baking soda in buttermilk just before adding to batter along with eggs and vanilla extract, mixing well. Pour into a lined muffin tin and bake 18-22 minutes.  Remove from pan and let cool completely before frosting.

Icing:

1 cup (2 sticks) of unsalted butter, room temperature
About 16 oz powdered sugar (use your best judgment based on local humidity and stiffness of icing)
1 tsp vanilla extract
1-3 Tbsp Coca-Cola®
brown food coloring (optional)

 Beat butter in large mixing bowl until slightly fluffy and a light yellow color.  Slowly add in the powdered sugar until the icing is a little thicker than you'd like the final product to be.  Add the vanilla extract and soda until the icing is the proper thickness.  Continue beating for 3 minutes until the icing is a fluffy, smooth consistency.  If using, gently mix in a couple of drops of brown food coloring to make the icing the color of soda foam.  Pipe or spread onto cupcakes.  Depending on how much soda you use and how long you beat it, you may have a little extra icing or be a little short.