Preheat oven to 350 degrees and grease a 9x13 baking pan.
In an electric mixer, cream butter and sugar until light and fluffy. Beat in eggs, one at a time and then the vanilla. In a medium bowl, combine the flour, graham cracker crumbs, baking powder and salt. Gradually add to the creamed mixture. Set aside 1 cup for topping.
Press remaining mixture into the 9x13 baking pan. Place peanut butter cups wide side down on the crust. Spray a large spoon with cooking spray and spread the marshmallow creme gently onto the peanut butter cups. Crumble the remaining graham cracker mixture over top.
Bake at 350 degrees for 40-45 minutes or until golden brown (mine were a little dark around the edges at 45 minutes). Cool on a wire rack and store in an air-tight container.
Recipe by DessertedPlanet.com at https://dessertedplanet.com/peanut-butter-cup-smore-bars/