Cupcakes: Preheat the oven to 350°F and line two 12-cup muffin pans with liners.
Prepare the cake mix per the instructions on the box using milk or buttermilk in place of the water. Use the same quantity of eggs and oil recommended. Bake the cupcakes per the directions until a toothpick inserted into the centers comes back clean. Remove from the muffin pan to a wire rack to cool.
Banana Pudding Filling: In a medium size mixing bowl, use an electric mixer to whip together the cream cheese, sweetened condensed milk and vanilla extract. Beat on medium speed for 1- 2 minutes or just until light and fluffy.
To the mixture add the instant vanilla pudding mix and milk..
Whip the ingredients together on medium-high speed for 2-3 minutes or until the mixture thickens. Fold in 1 cup of whipped topping by hand.
Slice and quarter the bananas just before adding to the custard to prevent browning. Fold the diced banana chunks into the vanilla pudding. (You can toss the bananas with lemon juice, if desired.)
Assemble: Using a sharp knife or a cupcake corer cut a cone in the center of each cupcake removing the cake. Leave a 1/2 inch border around the edge. (Avoid cutting all the way to the bottom.)
Sprinkle 1/2 of the crushed vanilla wafer crumbs into the bottoms of the cupcakes, reserving the remaining for garnishing. Spoon the banana pudding mixture into the centers.
Pipe a dollop of whipped topping on top and garnish with reserved vanilla wafer crumbs.
Chill for at least 2-4 hours, then serve.