In a large bowl, beat or quickly whisk together the sweetened condensed milk, pudding mix, and cold milk until thickened. Add the rum and whisk for 1-2 minutes more. Refrigerate for at least 10-15 minutes (following the package directions for the pudding).
In a large trifle dish or glass bowl, layer the Nilla wafers, pudding mixture, and whipped topping, until you reach the top of the bowl. Ensure that you finish with a layer of whipped topping. Refrigerate until ready to serve.
Before serving, top off with the crushed Nilla wafers for an added crunchy garnish.
Pro Tip: For adorable, individual banana puddings, layer the ingredients (as indicated in the instructions above) in Mason jars and garnish with a whole Nilla wafer and slice of banana.
