In bowl add rava, jaggery, banana, cashew, coconut, cardamom. Mash the banana without any lump. Mix them all to make a very thick dough by adding milk as needed. NOTE: if you make the dough soft it will break into pieces when you deep fry them.
Keep the dough aside for 30 minutes.
Now make small ball out of the dough. Flatten the balls and keep it aside.
Heat oil in a deep pan. Reduce the heat to medium low and deep fry the flatten balls to golden brown on both sides and serve. i.e. fry them like vadai