Put the curd, ginger + garlic paste, red chilli powder, biriyani masala and some salt in a mixing bowl.
Mix well with a spoon.
Then add some chopped mint + coriander leaves, half cup of brown onion and 3 Tablespoons of oil.
If possible try to use that oil in which you fried the onion.
Lastly add washed, deveined prawns. Mix well and keep it in fridge for 2 hours.
After the marination, take out the prawns from the fridge.
Spread a Teaspoon of oil in a vessel, in which you will make biriyani.
Then place the marinated prawns. Keep it aside.
Boil 2 - 3 cups of water in a saucepan.
Add all the whole spices and 2 Tablespoons of salt.
Add the washed basmati rice into the boiling water.
Cook the rice till become 85% soft.
Then immediately drain all the water and spread the half cooked rice over the marinared prawns.
Now very quickly spread saffron soaked milk, remaining brown onion, chopped mint + coriander leaves, kewra water and a Teaspoon of ghee.
Cover the pan with a tight lid and put some weight over it.
First place the vessel on high heat for 5 to 6 minutes. Then lower the heat and cook for another 20 minutes.
Let it rest for 10 minutes and then serve hot.