Cake Mix Cake Extender Use this extender for higher and lighter cakes 1 (18.25 ounce) box cake mix (any flavor) 1 cup all-purpose flour 3/4 cup granulated sugar 1 teaspoon baking powder 1/2 cup vegetable oil 2/3 cup water Prepare cake mix per package directions. Combine remaining ingredients and add to batter. Pour into greased 9 x 13-inch pan and bake per package directions, adding 15 extra minutes to baking time.