I am not sure how I came across this recipe but I remember making several of these pies for a restaurant. they are super easy, no fail - and extremely fattening!!!
nevertheless, they taste really good and are always a great backup if you have no idea what to make. The condensed milk turning into toffee always amazed me and i often have a can of ready made 'toffee' just in case! You can always use just a bit of it and use more bananas....

1 can of condensed milk
2 oz butter
1 oz sugar
8 oz digestive biscuits, crushed ( or use graham crackers)
8 oz digestive biscuits, crushed ( or use graham crackers)
1 large banana, sliced
1 cup whipping cream
Method :
Boil the unopened tin of condensed milk in a saucepan for about 2 hours, topping up with boiling water as necessary.
Boil the unopened tin of condensed milk in a saucepan for about 2 hours, topping up with boiling water as necessary.
Remove from the heat, leave to cool , then open the can. (I often boil a couple of cans as they keep well and that way I will have the 'toffee' ready for another time)
Melt the butter and mix in the sugar and biscuit crumbs.
Press the biscuit mixture into the base of a greased 20 cm/8 in cake tin .
The milk would now have become toffee like - spread this on the bottom
Top with the sliced bananas and then the whipped cream.