In a large bowl, whisk the instant vanilla pudding mix with the cold whole milk for about 2 minutes, until smooth and thickened.
Add the sweetened condensed milk and vanilla extract. Whisk until fully combined.
Cover the pudding mixture and refrigerate for 10 to 15 minutes to help it firm up.
Pour the cold heavy whipping cream into a separate bowl. Using an electric mixer, beat until soft to medium peaks form.
Gently fold the whipped cream into the chilled pudding mixture with a rubber spatula. Continue folding until smooth and evenly combined.
Slice the bananas into even pieces, about 1/4 inch thick.
Arrange a layer of vanilla wafers across the bottom of a deep serving dish.
Add a layer of banana slices over the cookies.
Spoon a layer of the creamy pudding mixture over the bananas and spread it evenly
Repeat the cookie, banana, and pudding layers until the ingredients are used.
Finish with a layer of pudding and decorate with additional vanilla wafers or other toppings if desired.
Cover and refrigerate for at least 4 hours. For the best texture, chill overnight.
Serve cold, scooping through all the layers so each portion contains pudding, bananas, and softened vanilla wafers.