Mix 1 tablespoon (3 teaspoons) of the tandoori masala powder, ½ teaspoon each of turmeric, curry powder, garam masala, cumin, and coriander powder with the yogurt, lemon juice, half of the minced ginger and garlic, and ½ teaspoon of salt.
Cover the chicken with the marinade, cover the bowl and refrigerate for at least an hour or preferably overnight.
Roast the chicken at hot 230°C/450°F/gas mark 8 for 15 minutes
Melt the ghee with the oil.
Add the onions, and the rest of the minced garlic and ginger.
Cook on high heat for 5 minutes.
Add the tomato paste, 1 teaspoon tandoori masala, ½ teaspoon turmeric, ¼ teaspoon each garam masala, coriander powder, and cumin, and 1½ teaspoon salt.
Cook on medium heat for 2 minutes, cover the pan and cook on low heat for 5 minutes while stirring occasionally.
Add the chilies, if using, and the cooked chicken.
Cook on medium heat for 3 minutes, then cover the pan and cook on low heat for 10 minutes.
Stir in the coriander and remove from heat.
Drain and rinse the rice.
Boil the rice with 6 cups (1½ l ) of water, then cover and lower the heat to a simmer for 5 minutes or until the rice is half cooked.
Drain any remaining water.
Alternate layers of rice and chicken in a large saucepan, starting and ending with rice.
Cover the pan and cook over very low heat for 10-13 minutes until the rice is cooked.