In a saucepan, cover an unopened can of sweetened condensed milk with water. Simmer for 3 hours, adding water as necessary to keep the can submerged in the water.
Heat the oven to 375 degrees F.
Mix the graham cracker crumbs, melted butter and a pinch of salt in a small bowl. Press the mixture into a 9-inch pie plate. Bake for 12 to 15 minutes, then cool completely and refrigerate until ready to assemble the pie.
Remove the condensed milk from heat and let cool enough to be able to remove the can from the water. Let cool another 10 to 15 minutes before opening the now dark and creamy toffee.
Thinly slice the bananas (1/4-inch) on the bias. Evenly arrange 1 layer of bananas over the cooled crust. Pour the toffee over the top and spread evenly. Put another layer of bananas on top of the toffee. Whip 2 cups of cream, in a large bowl, until soft peaks form and spoon it on top of the bananas, spreading it out to make an even layer.
Refrigerate the pie for at least 1 hour before serving. Good luck with that...I never make it!