Marinate chicken pieces with turmeric powder and salt for at least 1/2 hour.
Crush ginger, garlic and green chilies to a coarse mixture.
Heat oil and ghee in a heavy-bottomed pan. Add coarse ground ginger – garlic-green chilly mixture and cook for a minute. Add sliced onion, salt and saute for 7 – 8 minutes until the onion turns translucent. Add turmeric powder, chopped tomatoes and pepper powder. Cook for 3 – 4 minutes. Add yoghurt, ground biriyani masala powder, chopped cilantro and mint. Stir for a minute. Add chicken pieces. Mix well. Add 1/2 cup hot water and mix well. Cover and cook for about 30 minutes stirring occasionally until chicken pieces are done and gravy is thick. Add 2 tsp ghee, a tbsp of cilantro and mint leaves and switch off.
While the chicken is cooking, cook ghee rice. Heat a large 5 liter pressure cooker or any heavy-bottomed vessel with 3 – 4 tbsp ghee. Add the whole spices (Bay leaves – 3 – 4, Cardamom – 7 – 8, cinnamon stick – 1 inch piece, cloves – 8 – 10, star anise – 2.)
Stir for a few seconds until fragrant. Add sliced onion and cook for a couple of minutes until transparent. Add drained rice. Stir for a few seconds. Add 4.5 cups of hot water, enough salt and bring to a boil. Taste-check for salt, the water should be slightly salty. Cover with lid and cook until steam starts to come out profusely. Put on the whistle(if you are using pressure cooker). Bring down the heat to low and cook for 3 – 4 minutes. Switch off. Open the lid after 10 – 15 minutes. Fluff the cooked rice gently using a fork.
In a heavy-bottomed vessel (you can use the one in which you cooked chicken if it is oven-proof), spread half of the chicken masala in the bottom. Top it with half of the cooked ghee rice. Sprinkle fried onion, cashews, raisins, chopped mint, cilantro, few drops of rose water and saffron milk. Spread the remaining chicken masala on top followed by remaining ghee rice. Sprinkle fried onion, cashews, raisins, mint etc. Cover tightly with aluminium foil. Bake at 350 F for 30 minutes. OR Heat a large tawa at low heat. Place the biriyani pot and cook for 10 – 15 minutes. Switch off. Let it rest unopened for another 10 – 15 minutes in the biriyani pot. Mix gently.
Serve hot with raita, biriyani chammanthi, pappadam and date-lemon pickle.