The frosting is on the inside!
Cupcakes:
1-18-oz. yellow or butter cake mix (dry)
1 c milk
1/2 cup butter, melted
1/4 c sugar
1 t vanilla
1/8 t baking powder
3 eggs
Filling:
2 cups butter or margarine, softened
2 7-oz. jars marshmallow cream
2 c powdered sugar
1 1/2 t vanilla
dash salt
Line cupcake pans with 36 paper cupcake liners. Combine all cupcake ingredients and mix on low speed until combined. Mix at medium speed for 2 minutes until smooth. Fill cupcake liners half full. Bake at 350°F for 12-13 minutes or until barely golden. Remove from oven and cool on wire rack 5 minutes. Remove cupcakes from pan and cool completely.
Make filling by beating butter or margarine until creamy. Add marshmallow cream. Beat until combined. Add powdered sugar, vanilla and salt and beat on high speed until fluffy, 3-4 minutes. (Use filling immediately as it tends to get runny after a while.) Fill decorators bag with filling. (Use star or circle decorator tip.) Insert tip into center of cooled cupcake and squeeze bag to fill cupcake with 1-2 tablespoons filling. Cupcake will expand. Remove tip from cupcake and repeat until all cupcakes are filled.