Disappearing marshmallow bars

1 cup butterscotch chips

1/2 cup butter

1 1/2 cups flour 

2/3 cup brown sugar

2 teaspoons baking powder

1/2 teaspoon salt

1 teaspoon vanilla

2 eggs

2 cups miniature marshmallows

2 cups chocolate chips

Melt the butterscotch chips and butter in a pan. Cool to lukewarm. Add flour, sugar, baking powder, salt, vanilla and eggs. Fold in marshmallows and chocolate chips. Spread into a 9-by-13 greased pan. Bake at 350 degrees for 20-25 minutes. Do not over bake. Center will appear jiggly but will firm up upon cooling.