Fry the onions in hot oil till golden brown in colour (for marination and layering).
Into a large bowl, add all the ingredients mentioned 'for marinating chicken'. Combine well and marinate for 2 hours.
Heat oil in a large pan and add the marinated chicken mix, combine well and cook for a few minutes. After that, close the pan with its lid and cook covered till chicken pieces are almost done- about 90% cooked. Do not over cook the chicken.
Heat oil in a pan and add spices and required water. When it starts boiling, add rice and cook on medium flame.
I used the same wide pan used for cooking the chicken. Transfer the cooked chicken masala to a larger bowl and clean the pan well. Spread 1 tbsp of melted ghee on the pan. Layer the cooked rice as the first layer. Second layer: Chicken masala. Third layer: spread fried onions, cashew nuts, raisins, coriander leaves and mint. Spread ¼ tsp garam masala powder over the rice. Drizzle ½ tbsp melted ghee. Again layer with rice, chicken masala and topping. There will be 2 layers each for rice, chicken masala and toppings.
Then close the pan with its lid. Place the pan over low heat and cook or keep in dum for 20 minutes. After 20 minutes, remove the pan from the heat, and let rest covered for another 15 to 20 minutes.
While serving, combine the rice and chicken masala and serve on plates. This biryani can be served with raita, pappad, pickle etc.