This is my adult version of s'mores.

S'More Cookie Bars Makes 16 bars

1/2 c butter, softened
3/4 c sugar
1 egg
1 tsp vanilla
1 1/3 c flour
3/4 c graham cracker crumbs
1 tsp baking powder
1/4 tsp salt
4 Milk chocolate bars (1.55 oz each) (I prefer using Symphony Bars with toffee and almond chips but any chocolate bar will do)
1 c marshmallow creme

Heat oven to 350 degrees. Grease 8" square baking pan. In a large mixer bowl, beat butter and sugar until light and fluffy. Add egg and vanilla, beat well. Mix in flour, graham cracker crumbs, baking powder and salt. Mix till well blended.
Press half of dough into prepared pan. Arrange chocolate bars over dough, breaking as needed to fit. Spread with marshmallow creme. Scatter bits of remaining dough over marshmallow. Carefully press to form a layer.
Bake for 30-35 minutes or until lightly browned. Cool completely in pan on wire rack. Cut into bars.