Slice off the tops of the cakes to make them level.
Whip some of the cream beyond the "whipped cream" stage until it is near the "butter" stage. Place in refrigerator. This will be referred to as "hard cream" from now on.
Keep layers in place with shish-ka-bob skewers until serving.
Each cake mix makes 2 9-inch rounds. One batch of buttercream frosting can cover 2 cakes. Moral: Make 2 complete cakes - one for practice, the other for presentation.
Make the cakes per the instructions, but add 1 or 2 mashed bananas to the yellow cake. Bake in 9-inch round pans and let them cool.
From this point on: Everything should be refrigerated. If it is warm, whipped cream will melt and layers will move. Keep it cold!
Layer 1: Banana Place the yellow (banana) cake on your plate. Put a layer of sliced bananas (1/4-1/2 inch thick) over the cake, staying about 1/2 inch away from the edge. Get the hard cream and use a piping tool to pipe a border around the edge. Fill with pudding. Cover with whipped cream.
Layer 2: Strawberry Make a strawberry glaze (berries & sugar, cooked until thick). Let cool. Place the white cake on top of layer 1. Put a layer of sliced strawberries over the cake, staying about 1/2 inch away from the edge. Get the hard cream and use a piping tool to pipe a border around the edge. Fill with strawberry glaze. Cover with whipped cream.
Layer 3: Chocolate Make chocolate buttercream frosting. I just make a standard buttercream frosting, and add cocoa until it tastes chocolatey. Place the chocolate cake on top of layer 2. Spread buttercream frosting on top of cake.
Cover the whole layered monstrosity in whipped cream. Don't forget to remove bamboo skewers before serving.