Marinate the Chicken: Whisk yogurt, ginger garlic paste, lemon juice, chili powder, garam masala, cumin, turmeric, and salt; coat chicken; refrigerate at least 30 minutes or up to 8 hours.
Char the Tikka: Broil on high 6 inches from element for 8–10 minutes, turning once, until edges char in spots (or sear in a ripping-hot cast iron skillet 3–4 minutes per side). Set aside with juices.
Build the Masala Sauce: Cook onion in butter and oil 6–8 minutes until golden; add ginger garlic paste and chilies for 1 minute; add tomatoes, spices, salt, and water; simmer 10 minutes until thickened and oil glistens; blend smooth.
Combine and Finish: Stir in cream and kasuri methi; add charred tikka with juices; simmer gently 8–10 minutes until chicken is 165°F / 74°C and sauce coats a spoon. Adjust salt.
Serve: Drizzle with cream, scatter cilantro, and serve hot with basmati rice or naan.