EASY YUMMY UPSIDE DOWN CAKE 1 10-oz. pkg. miniature marshmallows 1 box cake mix, any flavor of your choice 1 can pie filling of your choice Spray a 13 x 9-inch pan. Pour marshmallows onto the bottom of the pan. Then prepare cake mix according to package directions and pour over marshmallows. Pour pie filling on top. Bake at 350 degrees for 40 minutes.