Creating a Banana Pudding Cake involves several steps, but following this clear guide will make the process simple.

1. Preheat the Oven: Start by preheating your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. Mix Dry Ingredients: In a large bowl, combine the flour, sugar, baking powder, and salt.
3. Cream Butter and Sugar: In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
4. Incorporate Eggs: Add the eggs one at a time to the butter mixture, mixing well after each addition.
5. Add Bananas: Stir in the mashed bananas and vanilla extract until the mixture is smooth.
6. Combine Mixtures: Gradually add the dry ingredients and milk to the banana mixture, alternating between the two until fully combined.
7. Bake the Cake: Pour the batter evenly into the prepared cake pans. Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
8. Cool Down: After baking, remove the cakes from the oven and let them cool in their pans for about 10 minutes before transferring them to wire racks to cool completely.
9. Prepare the Pudding: While the cakes cool, mix the instant vanilla pudding mix with 4 cups of cold milk, whisking until thickened.
10. Assemble the Cake: Once the cakes are cooled, place one layer on a serving platter. Spread half of the pudding mixture over the first layer.
11. Add Topping: Top the pudding with half of the whipped topping. Place the second layer on top and repeat the process with the remaining pudding and whipped topping.
12. Garnish: Decorate the top with banana slices and crushed vanilla wafers for added flair.
13. Serve: Chill the assembled cake in the refrigerator for about an hour before slicing and serving.