Strawberry Upside Down Cake 1 (18.25 ounce) box white cake mix 1 (6 serving size) box strawberry gelatin mix 2 (10 ounce) packages frozen strawberries, thawed 1 (10.5 ounce) package mini marshmallows Preheat oven to 350. Place single layer of marshmallows into greased 9x13 inch baking pan. Prepare cake batter as directed on package. Pour over marshmallows. In bowl, combine gelatin mix and strawberries. Pour over batter. Bake as directed on package.