Make the salted caramel:
Sprinkle the sugar in an even layer in a medium heavy-bottomed saucepan set over medium heat. Using a heatproof rubber spatula, stir the sugar constantly until it begins to melt and darken in color. (If chunks form, continue stirring until they dissolve.) Stop stirring and let the sugar cook, undisturbed, until it turns amber in color.
Remove the melted sugar from the heat and whisk in the butter until combined, then slowly and carefully whisk in the heavy cream. (It will bubble vigorously.)
Stir in the sea salt then transfer the caramel to a glass container to cool while you prepare the pudding.
Make the banana pudding:
In a large bowl, whisk together the milk with the instant vanilla and banana pudding mixes.
In a separate medium bowl, stir together the cream cheese and condensed milk.
In the bowl of a stand mixer fitted with the whisk attachment, whisk the cold heavy cream on high speed until stiff peaks form.
Fold the whipped cream into the cream cheese mixture.
Stir the cream cheese mixture into the pudding until well combined. Refrigerate the pudding until ready to serve.
When ready to serve, place a layer of Nilla Wafers on the bottom of your serving dish, and then top the wafers with a layer of the pudding, followed by a layer of sliced bananas and a drizzle of the salted caramel sauce. Repeat the layers as needed. (See Notes.)
The amount of Nilla Wafers you will need depends on how you serve the pudding. You can serve the pudding in a 13-by-9-inch baking dish, or make individual banana puddings in your desired serving dishes, such as mason jars, tall glasses or ramekins.
When making caramel, it's really important to use a heavy-bottomed saucepan and to never turn your back on the sugar. It can change from amber to black in a second!
This recipe will yield about 1 cup of caramel. Use a portion of it with the pudding and save the rest, stored in an airtight container in the fridge, for sundaes ... or for eating by the spoonful.