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.

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.