Remove the label on the condensed milk and submerge the unopened can in pot of water. Cover and boil for 2 1/2 hours. Leave on a simmer or light boil for 2 hours topping off with water as needed. Be sure to keep the can covered by water at all times!!!
Remove from heat and let cool before opening. Condensed milk should be thick and a nice caramel color.
This can be done ahead of time.
Slice bananas into crust.
Open tin and pour over sliced bananas
For the whipped cream (*You can skip this step entirely by using cool whip.) whip cream until stiff peaks are just about to form then beat in vanilla until peaks form. Spread whipped cream over the top of caramel mixture.
Spread whipped cream over the top of caramel mixture. Put in fridge to set for at least 1 hour
(I like to sprinkle a little Cinnamon over the top but it's optional. You could also grate chocolate or drizzle some of the caramel mixture.)