Begin by marinating the chicken. Just add all marinade ingredients to the chicken thighs, mix well, and keep it aside.
Now cook the rice. For this, wash the rice thoroughly. Bring about 4 cups of water to boil, add the rice along with the aromatics. Check for doneness after a while. It should be al dente. Drain and keep aside.
It's time to make the biryani. In a deep and wide pot, heat the oil. Add the chopped onions and fry till they soften. Add the marinated chicken along with the marinade and cook till you see the oil separating at the edges.
Lower the heat, cover the pot with a lid, and cook for about half an hour or till the chicken is tender. You should have chicken with a thick spicy paste.
Now comes assembling. For this, we will create two layers of chicken and rice. Remove half the chicken along with the paste. On top of the remaining cooked chicken, put half the cooked rice. Spread half the crisply fried onion along with half the coriander and 1 tbsp of ghee.
On the surface of the rice, spread the rest of the chicken you had kept aside. Now comes the layer for the rest of the rice. Level the rice surface and spread over the aromatics. This will be the rest of the crisply fried onions and coriander. Pour over the soaked saffron along with 1 tbsp of ghee, mace, the nutmeg, and the garam masala.
Cover the pan and place some kind of weight on it, such as a kettle full of water. It should be cooked under indirect heat. So if possible, place the pot over a big skillet. If you don't have one, place the pot directly on the stove. Cook over medium heat for around 30 minutes.
Your biryani is ready! You will get a hit of the lovely aromatics the moment you open the lid.