S'mores Sandwich Bar Cookies

I doubled this and made it in a 9x 13

Ingredients:

•1/2 cup (1 stick) butter or margarine, softened
•3/4 cup sugar
•1 egg
•1 teaspoon vanilla extract
•1-1/3 cups all-purpose flour
•3/4 cup graham cracker crumbs
•1 teaspoon baking powder
•1/4 teaspoon salt
•1-1/3 cups (8-oz. pkg.) HERSHEY'S Mini Milk Chocolate Bars OR 5 HERSHEY'S Milk Chocolate Bars (1.55 oz. each)
•3 cups miniature marshmallows
Directions:

1. Heat oven to 350°F. Grease 8-inch square baking pan.

2. Beat butter and sugar until well blended in large bowl. Add egg and vanilla; beat well. Stir together flour, graham cracker crumbs, baking powder and salt; add to butter mixture, beating until blended. Press half of dough in prepared pan. Bake 15 minutes.

3. Sprinkle mini chocolate bars over baked layer or arrange unwrapped chocolate bars over baked layer, breaking as needed to fit. Sprinkle with marshmallows; scatter bits of remaining dough over marshmallows, forming top layer. Bake 10 to 15 minutes or just until lightly browned. Cool completely in pan on wire rack. Cut into bars. 16 bars.