01 - Combine chicken with yogurt, lemon juice, turmeric, cumin, garam masala, chili powder, and salt in a large bowl. Mix thoroughly, cover, and marinate for at least 10 minutes, or up to 1 hour for deeper flavor penetration.
02 - Heat 1 tbsp butter and oil in a large skillet over medium-high heat. Add marinated chicken pieces and cook for 5-6 minutes, turning occasionally, until lightly browned but not fully cooked through. Remove chicken and set aside, reserving juices.
03 - Add remaining 1 tbsp butter to the same skillet. Sauté onions for 3-4 minutes until soft and golden. Add minced garlic and grated ginger; cook for 1 minute until fragrant, being careful not to burn.
04 - Stir in coriander, paprika, and cayenne pepper. Cook for 30 seconds to bloom spices. Add crushed tomatoes and sugar; simmer for 5 minutes, stirring occasionally to develop flavors.
05 - Return chicken and accumulated juices to the skillet. Simmer for 8-10 minutes, or until chicken is cooked through and sauce begins to thicken slightly.
06 - Reduce heat to low. Stir in heavy cream and simmer for 2 more minutes to combine flavors. Adjust salt to taste. Serve hot, garnished with chopped cilantro alongside steamed rice or naan bread.