• In a bowl, combine chicken with all the ingredients for the chicken marinade; let marinate for  an hour (or overnight).
• Heat oil in a large skillet or pot over medium-high heat. When sizzling, add chicken pieces in batches. Fry until chicken is brown. Set aside and keep warm.
• Heat butter or ghee in the same pan. Fry the onions until they are little brown
• Add garlic and ginger paste and sauté for 1 minute until fragrant, then add ground coriander, cumin and garam masala. Let cook for about 20 seconds until fragrant, while stirring occasionally.
• Add crushed tomatoes, chili powder and salt. Let simmer for about 10-15 minutes, stirring occasionally until sauce thickens and becomes a deep brown red color.
• Remove from heat, scoop mixture into a blender and blend until smooth. You may need to add a couple tablespoons of water to help it blend (up to 1/4 cup).
• Pour the puréed sauce back into the pan. Stir the cream or yogurt and crushed kasoori methi (or fenugreek leaves) through the sauce. Add the chicken with juices back into the pan and cook for an additional 8-10 minutes until chicken is cooked through and the sauce is thick and bubbling.
• Garnish with chopped cilantro and serve with fresh, hot steam rice.

Notes
OPTIONAL: To thin out the sauce, add a couple tablespoons of ghee or butter at the end of cooking, and gently simmer it through. Alternatively, add a small amount of water.