S'mores Bar Cookies

This is one of my favorite summer recipes. It is easy to make, and much less messy than regular s'mores.

Gluten-Free S'mores Bar Cookies

1/2 c. butter or margarine
3/4 c. sugar
1 egg
1 tsp vanilla
1 1/3 c. GF flour blend
3/4 c. GF graham cracker crumbs 
1 tsp baking powder
1/4 tsp salt
1 bag semi-sweet chocolate chips (or to taste)
3 c. mini marshmallows

Preheat oven to 350. Cream butter and sugar. Add egg and vanilla. Add flour, graham crackers, baking powder, and salt. Press half of the dough into the bottom of a greased 9x13 pan. Bake 15 minutes. Sprinkle the chocolate chips on the bottom crust and top with marshmallows. Scatter bits of remaining graham cracker dough over marshmallows. Bake at 350 for 10-15 more minutes until lightly browned.