Thanks everyone for all the great ideas! I ended up using a recipe I found online that took a stick of butter, a jar of marshmallow fluff, 1 1/2 cups of powdered sugar, and cream cheese flavoring. I thought it turned out very good but my daughter tried it and thought it was too sweet. The only problem I had was having it run on the top of the cupcakes because it was very loose so when I piped it, it spread out a lot.
1/24/15 at 6:57am