Preheat oven to 350 degrees.

To make the first layer, mix together cake mix, egg, sprinkles and oil. Press into greased 9x9 inch pan. Bake at 350 degrees for 10-12 minutes.

For the second layer, remove the cake mix layer from the oven and put spoonfuls of the marshmallow cream on top. Allow the marshmallow cream to heat and spread out on its own.

While waiting, make the top layer. Microwave 1½ tablespoons of butter for 20 seconds in a large bowl, until melted. Add 3 cups of mini marshmallows and stir to coat. Microwave for 45 seconds and stir until smooth. (If the marshmallows aren’t completely melted, microwave for an additional 30 seconds.) Mix in 3 cups of crisped rice cereal.

Carefully spread the marshmallow cream out evenly. Then, drop the crisped rice mixture by large spoonfuls over the marshmallow cream layer and carefully spread out evenly.

Allow the bars to cool and set before cutting them into squares. They spread once they are cut, so you might want to wait to cut them until right before serving.