Adapted from Hershey's Kitchen
1/2 cup butter, at room temperature
1/4 cup brown sugar
1/2 cup sugar
1 teaspoon vanilla
3/4 cup graham cracker crumbs
1 1/3 cups flour
1 teaspoon baking powder
1/4 teaspoon salt
5 1.55 ounce Hershey's Milk Chocolate Bars
1 7-ounce jar marshmallow creme
Preheat oven to 350º. Line 8 inch square baking pan with non-stick foil or grease well.
In a large mixing bowl, cream butter and sugars. Mix in egg, then vanilla. In a smaller bowl, whisk together graham cracker crumbs, flour, baking powder and salt. Add to butter mixture and mix till combined.
Press half of cookie dough into bottom of prepared pan, then top with a layer of Hershey bars, breaking as needed to cover dough. Spread marshmallow creme over chocolate. Flatten small bits of dough to cover top of marshmallow cream completely. Spread with offset spatula if needed.
Bake for 30-35 minutes. Cool completely before cutting.