Heat the oil. Add dry red chillies and saute for 1 minute. Add shallots and saute till golden brown. Add the ginger garlic paste and saute for a few sec more till the raw smell goes off.
Take the pan off the fire and let the mix cool a bit. Grind the mix to a paste using a little water if required.
Heat a thick bottomed pan or kadhai, drop in the ground paste along with prawns, some turmeric powder, salt and curry leaves. Mix it all well.
Cook covered with a lid, till the prawns are tender, sprinkle some water if the masala seems to be sticking. The gravy needs to be thickish so don't use too much water.
In a small tadka pan, heat ghee and roast cashews till lightly browned. Add to the prawn mixture. You can skip this but I love the crunch it adds.
In a glass bowl, pour the coconut milk. Over that, slowly pour the cooked prawns. Do not stir. The coconut milk will slowly form an outer layer. The layering is what makes it look beautiful. Let me repeat, do not stir. The milk will merge in when you are serving.
The curry is perfect with rice or dosa or appams.