Make the pudding first so it has time to set. In a medium bowl, whisk together the instant pudding mix and cold milk for about 2 minutes until it begins to thicken. Cover the bowl with plastic wrap and refrigerate for at least 10 minutes.

While the pudding chills, caramelize the bananas. Melt the butter in a medium skillet over medium heat. Add the brown sugar, cinnamon, and salt and stir to combine. Let it bubble for about 30 seconds, then add the banana slices in a single layer.

Cook the bananas for 2 minutes without moving them so they get some golden color on the bottom. Gently flip each slice and cook for another 1 to 2 minutes until they are soft, glazed, and deep golden. Do not cook them until they fall apart. Remove from heat and let them cool for 5 to 10 minutes.

Crush the vanilla wafers into rough crumbles. You can put them in a zip-top bag and crush with your hands or a rolling pin. You want some crumbs and some small pieces, not fine powder.

Layer each jar or ramekin starting with a layer of crushed wafers on the bottom. Add a layer of vanilla pudding, then a few caramelized banana slices with their caramel sauce. Add another layer of crushed wafers, then more pudding, finishing with a few more banana slices on top.

Cover each cup loosely with plastic wrap and refrigerate for at least 2 hours so the layers set and the wafers absorb the pudding slightly.

Right before serving, whip the cold heavy cream with powdered sugar and vanilla using a hand mixer or stand mixer until soft peaks form, about 2 to 3 minutes. Add a dollop of whipped cream on top of each cup and serve cold.