Whisk together milk, sweetened condensed milk, vanilla, and salt in a large bowl until smooth.
Sprinkle in pudding mix; whisk 2 minutes or until no lumps remain. Chill 5 minutes or until set. Fold three-fourths of the whipped topping into the pudding.
Arrange a layer of cookies in the bottom of a trifle dish or bowl. Add a layer of bananas over cookies; place another layer of pudding over bananas and smooth using a spatula. Repeat layers 3 times or until you reach the top of the dish.
Top pudding with remaining whipped topping. Garnish with more bananas and crushed cookies, if desired.
Notes
Try and use the entire box of vanilla wafers. The more cookies you use, the better the pudding will be (in my opinion).