Peanut Butter Cup S'mores Bars

Peanut Butter Cup S'mores Bars
Ingredients
1/2 cup butter, softened
1/2 cup packed brown sugar
1/4 cup sugar
1 egg
1 teaspoon vanilla
1 1/4 cups flour
1 teaspoon baking powder
1/4 teaspoon salt
1 cup graham cracker crumbs
16 peanut butter cups, regular size
1 1/2 cups marshmallow fluff*
Source Link: http://melssweetlife.com/2012/04/05/peanut-butter-cup-smores-bars/