Melt butter on low fire (set aside about 5 tablespoons) and add sugar. Pour 3/4 of the condensed milk and stir. Continue stirring (make sure it is on low fire as it burns easily) for 10-15 minutes or until light brown. Another way to make toffee/caramel is to put unopened condensed milk (can) in a pot of water and bring to boil on low fire (make sure it is submerged in water) for 2 hours. Let it cool for 45 minutes and then open can.
Mix crushed graham crackers (set aside a few tablespoons for decoration) with remaining melted butter and press on to the base of the cake pan. Make sure to cover holes/gaps. Slice bananas (set aside a few slices for decoration) and arrange on top of the graham cracker base/pie crust.
Pour toffee/caramel on top of sliced bananas and spread evenly.
Whisk/beat cream and remaining conedensed milk until stiff. Pour on top of toffee.
Decorate top with remaining crushed grahams and sliced bananas. To keep sliced bananas from turning brown, soak them in water with lemon juice or vinegar first. Chill for 3-4 hours and serve.
