I found this recipe and another blog, started by a 13 year old. She loves to bake and is very good at it . Good for her !!!
This is real simple.. Prepare and bake a box cake according to the package instructions and let the cupcakes cool.
Light and Fluffy Cream Filling
3/4 cup shortening
2/3 cup confectioner's sugar
1 cup marshmallow creme
1 tsp vanilla extract
In a large bow, cream the sugar and shortening until it's light and fluffy. Add the marshmallow creme and vanilla and mix well
Cut a small hole in the corner of a plastic bag or use a Pastry Bag, Fill the bag with the cream and push the tip of the bag down the center of the cupcake and squeeze the bag to release the filling. The cupcake may expand a little.
If you would like to check out this site the address is http://www.bitemebaker.blogspot.com/