DirectionsHeat oven to 375F.
Line 13x9-inch baking pan with aluminum foil, extending foil over edges.
Spray foil with no-stick cooking spray; set aside.
Combine sugar, melted butter, egg and vanilla in bowl; mix well.
Add 1 cup graham cracker crumbs, flour, baking powder and salt; stir just until combined.
Spread into prepared pan.
Bake 8 minutes.
Remove from oven; sprinkle partially baked crust with marshmallows, chocolate chips and 1/4 cup graham cracker crumbs.
Continue baking 5-10 minutes or until marshmallows are golden brown.