01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish thoroughly with butter or cooking spray.
02 - In a medium bowl, beat softened cream cheese with granulated sugar until completely smooth and creamy. Add the egg and vanilla extract, mixing until fully incorporated. Spread this mixture evenly across the bottom of the prepared baking dish.
03 - Arrange sliced bananas in a single, even layer over the cheesecake mixture, covering as much surface area as possible.
04 - In a separate bowl, whisk together the instant banana pudding mix and cold milk for 2 minutes until the pudding thickens noticeably. Pour this over the banana slices and spread gently to create an even layer.
05 - Sprinkle the crushed vanilla wafer cookies evenly over the pudding layer, creating a uniform crust.
06 - Evenly distribute the dry yellow cake mix over the wafer layer. Do not stir or mix the layers.
07 - Drizzle melted butter over the dry cake mix, trying to cover as much surface area as possible. The butter will help create a crispy, golden topping.
08 - Bake for 45-50 minutes, or until the top is golden brown and the center appears mostly set. A slight jiggle in the center is acceptable as it will continue to set while cooling.
09 - Remove from oven and let the cake cool for at least 30 minutes before serving. This allows the layers to set properly.
10 - While the cake cools, whip the cold heavy cream with powdered sugar and vanilla extract using a hand mixer or whisk until soft peaks form.
11 - Serve the dump cake warm or chilled, topped with dollops of whipped cream. Garnish with additional banana slices and vanilla wafers if desired.