In the bowl of an electric stand-mixer (using the whisk attachment), mix together the ice cold water (start with 3 cups and work to 4 cups if needed based on the consistency of pudding), vanilla pudding mix, and sweetened condensed milk until thick, about 10 minutes on medium-high speed. NOTE: The mixture should look like pudding. NOTE: If using a hand-mixer instead, you may need an EXTRA BOX of vanilla pudding to ensure that the consistency is creamy and not too 'watery'.
Finally, add in vanilla extract, salt and mix for another minute or so.
Gently fold in the homemade whipped cream (or Cool Whip) into the pudding mixture using a spatula until, well incorporated.
In a trifle bowl (or your favorite dish), layer peanut butter sandwich cookies, vanilla wafers (if using), sliced bananas, melted peanut butter, and pudding mixture; repeat layering until all ingredients have been used.
Garnish top with remaining peanut butter cookies + vanilla wafers (crushed) and Refrigerate for at least 4 hours before serving. Best if chilled overnight.