heat oven to 350°F. grease 8inch square baking pan

beat butter and sugar in large bowl until well blended. 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 into prepared pan. bake for 15 minutes.

sprinkle chocolate bar sections, marshmallows and bits of remaining dough over baked layer. bake 10 to 15 minutes or just until lightly browned. cool completely in pan on wire rack. cut into bars.