Bake 18 to 20 minutes or until edges and tops are set. Remove from oven, and top each brownie cup with two marshmallow halves; return to oven 1 to 2 minutes or until marshmallows are softened. Cool 5 minutes in pan. Remove from pan; cool 5 minutes. Top each with 1 teaspoon graham cracker crumbs and 2 chocolate bar pieces.