Step 1:wash the rice and soak for 30 minutes. Step 2: in a pressure cooker, add some mustard oil and heat it up and sprinkle some water. Step 3: add the marinated baby potato and fry for 4-5 minutes until a golden layer forms on the baby potato, and keep them aside. Step 4: in 2 liters of water add the whole spices and salt, let it come to boil. add the rice at boiling point and cook the rice until 70% done. Step 5: add the marinated Chicken in the remaining oil and fry it for 2-3 minutes, add the fried potato and kolkata biryani masala and salt to it and saute for 2 minutes. Step5:layer the rice over the Chicken and potato. Step 6: take 100 ml of warm milk add one gram of kolkata biryani masala, mix it well and pour over the layered rice. Step 7: add the ghee, brown onion and chopped coriander over the top layer and cook it in low flame till one whistle Step 8: let the pressure escape on its own, and serve it with raita.