Step 1: In a large mixing bowl, beat together the cold milk and sweetened condensed milk until well combined.
Step 2: Whisk in the instant vanilla pudding mix and vanilla extract for 2 minutes until the mixture thickens and is free of lumps.
Step 3: Gently fold in half of the thawed whipped topping until the pudding base is light and uniform.
Step 4: Cover the bottom of a 9x13 inch baking dish with a single layer of vanilla wafers.
Step 5: Place a layer of sliced bananas over the wafers, ensuring the fruit is evenly distributed.
Step 6: Spread half of the pudding mixture over the banana layer.
Step 7: Repeat the layers of wafers, bananas, and pudding, finishing with a final layer of whipped topping and crushed wafers for decoration.
Step 8: Refrigerate for at least 4 hours (ideally overnight) before serving to allow the wafers to soften into a cake-like texture.