The name of these soda fountain cupcakes says it all, although if you want it broken down further, root beer cupcakes and cream soda buttercream frosting are what these really are. And yes, the cupcake batter contains actual root beer, along with root beer extract, apple cider vinegar, vanilla extract and a few other, more basic, ingredients. The frosting consists of cream cheese, powdered sugar, butter and cream soda extract. Now those are soda fountain cupcakes.
Source Cupcake Project