In a bowl, combine your milk, instant vanilla pudding, 1 cup of eggnog, and your condensed milk.
Stir well and place in fridge to set for 15 minutes or until pudding has thickened.
While pudding is setting, place your heavy whipping cream and 1 cup of eggnog in your cold whipping bowl and combine until stiff peaks form. Reserve 1/2 cup of your whipped cream for your garnish.
Gently fold your vanilla pudding into your whipped cream mixture.
Slice your bananas into 1/2 inch rounds and crush your wafers into medium chunks.
Start layering your mason jars. Start with crushed wafers, then pudding, then 3-4 banana slices.
Continue layering until you reach the top. Then top with some eggnog whipped cream, some crushed wafers, and a sliced banana.
Serve immediately or it's best if left to sit in the fridge for an hour so the wafers soften.