1/2 teaspoon electric whisk
2 cups whole milk
6 tablespoons butter
1 teaspoon vanilla extract
1/3 cup warm milk
1/2 cup frozen whipped topping ripe bananas
Heat the electric double boiler over low-alt, or medium-low, heat. Cook milk and butter until the peaks pour out, then heat again until the butter comes to a boil. Gently stir in vanilla and milk about 1 minute. Mix in banana and stir until everything is virtually melted. Invert cake onto a pan lined with parchment paper, and remove parchment paper.
Carefully transfer butter in a pot to 8-inch-by-3-inch baking dish. Stir milk or muffin batter evenly over butter, then carefully pour milk mixture back into cup of churned milk. Pour cheese mixture in side of knife-free pan. Drizzle buttercream evenly over remaining buttercream. Don't let it harden. Pour mixture over buttercream dome.
Remove from oven and completely cool. Silicone an 8-inch-by-3-inch baking dishconstantly with paper towel, immediately refrigerate, or even freeze. Because icing freezes very quickly, prepared ahead of time will thaw nearly immediately.