For the saffron infusion, in a small mortar, crush the saffron into the warm milk. Alternatively, let the saffron sit in the warm milk for about 15 minutes.
Put the well crumbled mawa/ khoya in a thick walled pan or wok with the sugar. Cook over medium heat, stirring frequently, till it becomes a thick paste. Stir in the saffron-milk mixture and keep cooking and stirring until it becomes thick like a dough.
The mixture will begin to leave the sides of the pan/ wok. This should take about 5 to 10 minutes at the most. Mix in the ghee, cardamom and pistachios at this point. Take it off the heat and turn the mixture out onto a plate. Otherwise it will continue to cook in the pan/ wok and could start browning.
Let it cool a bit until you can handle the heat comfortably. Grease your Modak mould with a little ghee. Close the mould and tightly pack a little bit of the cooked mixture into the moulds. Gently open the mould and unmould the Modak to a plate. Working quickly repeat with remaining mixture.
Cover and let it sit at room temperature overnight to set. The next day the Modak should be firm to touch but soft to eat. This will keep at room temperature for a couple of days. This recipe makes a small batch of about 20 to 25 small Modak.