In a large pressure cooker, put in the condensed milk tins, fill it with water till the tins are totally submerged in it. See to it that the water level is above the tins.
Pressure cook this for two whistles on a high heat, then lower the heat and cook for 20 minutes more.
Then remove from heat, once cooled carefully remove the tins from the cooker and let them cool completely.
The condensed milk caramelizes and becomes like a toffee. This is called Dulce De Leche.
In the meantime, start preparing the base of the pie. Keep aside 4-5 Oreos, and crush the rest of the Oreos. Add in softened butter and mix well.
Take your serving dish, put in this mixture, spread and smoothen to make the base.
Refrigerate to let it set. (I put it in the freezer for about 10 minutes). Now whip the cream till stiff peaks form. Then refrigerate it.
Chop the bananas and keep it aside.
Lightly beat the DDL (Dulce de Leche). Chop the oreos that had been kept aside to decorate on top of the whipped cream.
Take out the pie base, cover it with the Dulce de leche, then add the bananas and raisins/dried berries, sprinkle some cinnamon powder on top, now cover with the whipped cream.
Chill for an hour before serving. Enjoy!