1. Melt butter or margarine in an 8x8x2-inch baking pan in oven, while oven is heating.
2. Peel bananas; cut in half, length wise and crosswise, to make 8 pieces. Arrange bananas, cut-side down, in melted butter, to resemble spokes on a wheel.
3. Spoon pineapple sundae topping in every other space between banana pieces. Spoon strawberry preserves in alternate spaces. Spoon pineapple sundae topping into center of pan to level of banana pieces.
4. Prepare cupcake mix with milk, egg and vanilla, following label directions. Pour over prepared fruits.
5. Bake in moderate oven (350°) 50 minutes, or until center springs back when lightly touched with fingertip. Remove pan from oven and cool on wire rack 5 minutes; loosen cake from sides of pan with a knife; invert onto
. serving plate.
6. Cool cake slightly. Just before serv ing, spoon thawed whipped topping into center of cake and garnish with walnut sundae topping.