Wash and chop the mangoes into cubes and evenly spread them in a baking dish.

Spread choco chips and walnuts over the mangoes.

In a bowl take all purpose flour, oats, butter, sugar, cinnamon and cardamom powder and with the help of fingers mash the butter into the flour till the flour take a crumbly texture just like bread crumbs.

Spread this crumbly mixture evenly over the mango in the baking dish.

Press gently and put it in a pre heated oven at 180 degree for about 15-20 minutes... or till the upper layer turns golden brown.