Dice Chicken and prepare Marinade. Put everything into a bowl or large Ziploc bag. Cover and Refrigerate for 30 Minutes to overnight. Overnight is ideal.

In a Large Skillet, heat 2 or 3 Tbsp of Oil over Medium Heat. When hot, add the Chicken. Cook for a few minutes on each side, until both sides are browned. Do not overcrowd the pan, and cook Chicken in batches, if necessary. The Chicken will finish cooking in the gravy, so don't worry about it being 100% cooked. Remove Chicken, set aside and keep warm.

In the same Skillet, heat the rest of the Oil and the Butter over Medium Heat. Add Onions. Cook until they start to soften and look translucent, about 5 Minutes. Add Garlic and Ginger and cook for another 1 to 2 Minutes. Add Cumin, Coriander, and Garam Masala. Stir while allowing the herbs to toast for about a Minute.

Add Tomatoes, Salt, and Kashmiri Red Pepper. Let simmer, stirring frequently for about 10 Minutes, or until Tomato mixture is thick and Dark Red/Brown.

Turn off heat. Spoon Tomato Mixture into a Blender, and blend until smooth. Add some Milk to the Blender if Tomatoes are too thick. Pour Gravy back into Skillet. Pour in Milk, Sugar, and Kasoori Methi. Stir well. Add Chicken back to Skillet. Heat to Medium and cook for another 10 Minutes or so, until the Chicken is fully cooked and the Gravy is thick and hot.

Garnish with Cilantro and serve over some Jasmine or Basmati Rice. Enjoy!