Marinate mutton with salt, lemon juice, white pepper, biryani masala, yogurt and Ginger Garlic Green chili paste. Keep airtight for atleast 2-3 hours Or Overnight Refrigerated.
Make a paste of pre soaked Cashews and milk.
Deep Fry thinly sliced onions till golden brown. Keep them aside to cool.
Saute whole spices and bay leaves in the oil in which onions were fried. Add a sliced onion and fry till translucent. Add the marinated mutton, cook in high heat for 5 mins.
Add chopped coriander and mint leaves. Pressure cook for 3-4 whistles on medium heat or till 85-90% cooked. Reduce the excess water from the gravy. Add cashew paste and fresh cream.
Boil water with whole spices, salt, bay leaves, lemon juice with the peel, coriander mint leaves, green chilies. Once rapidly boils, add the soaked basmati rice. Cook on High heat for 6-7 mins or till the rice is 85-90% cooked. Check if the rice breaks with a slight crunch. Drain it aside.
Prepare a flat pan and place the biryani pot on top. Layer the cooked mutton first. Spread it out. The mutton curry should have some gravy and not completely dry. Then layer with the rice. Add chopped coriander, mint leaves and fried onions, ghee. Then Add another layer of rice, coriander mint leaves, fried onions and ghee.
Cover with an Aluminum foil or a cloth. Then cover with a lid. Cook on High Heat for 3-4 Mins, then cook on Low Heat for 15 Mins. Open the lid after 15 mins of resting.