Marinate: whisk yogurt, lemon juice, tandoori masala, chili powder, ginger, garlic, salt; coat chicken, refrigerate 1-8 hours.
Broil marinated chicken 5-7 min until lightly charred at edges (does not need to cook through).
Melt butter in skillet; cook onion 6-8 min until soft and golden.
Add garlic, ginger, cook 1 min; add garam masala, cumin, coriander, turmeric, cardamom, stir 30-45 seconds.
Stir in tomato paste 1 min; add passata, sugar, salt; simmer 10-12 min until slightly thickened.
Blend until silky (optional) with immersion blender.
Nestle broiled chicken into sauce; simmer 8-10 min until cooked through.
Reduce heat to low; crush kasuri methi over pan, stir in cream; simmer 2-3 min (do not boil).
Serve over basmati rice or with naan, drizzle cream, scatter cilantro.