Mix chicken, ginger garlic paste, and yogurt in a bowl and marinate for an hour.
Soak cashew nuts and poppy seeds in 2 tablespoons of warm water each for 10 minutes.
Transfer the soaked cashew nuts and poppy seeds to a blender along with the water they were soaked in. Add green chilies to the blender and blend to make a smooth paste.
Heat 3 tablespoons of ghee and oil. When the ghee is hot, add cloves, black peppercorns, cinnamon, green cardamoms, black cardamoms, and dry red chilies to the pan and saute for 10-15 seconds.
Pick chicken pieces from the marinade and add them to the pan. Fry for 4-5 minutes, stirring frequently.
Add the remaining marinade, cashew nut and poppy seeds paste, white pepper powder, salt, and garam masala powder to the pan and mix well.
Add onion paste and 1 cup of water to the pan and mix well. Reduce the heat to low.
Cover the pan with a tight-fitting lid and cook for 40-50 minutes, until the chicken is cooked well. Stir a few times while cooking.
Finally, add 1 tablespoon ghee and kewra essence and mix well. Check for salt and add more if required. Garnish with saffron soaked in milk and serve!