Marinate the chicken Combine all marinade ingredients in a bowl and whisk until smooth. Add chicken pieces and toss to coat every surface. Cover and refrigerate for 2 to 4 hours minimum overnight produces the best results. The yogurt lactic acid gently tenderizes the chicken while the spices penetrate the meat.
Broil the chicken Preheat broiler to high. Place marinated chicken pieces on a wire rack set over a rimmed sheet pan. Broil on the top rack for 8 to 10 minutes, turning once halfway, until the chicken has charred edges and is cooked through at 165F. The char is essential it adds smokiness that defines chicken tikka masala. Set aside.
Caramelize the onions Heat ghee in a large heavy-bottomed skillet over medium heat. Add diced onion and cook, stirring frequently, for 12 to 15 minutes until deeply golden not just soft. This step builds the sweet flavor base of the entire sauce. Do not rush it.
Add aromatics and tomato paste Add minced garlic and grated ginger to the golden onions. Stir for 60 seconds until fragrant. Add tomato paste and stir constantly for 2 to 3 minutes until it darkens slightly and loses its raw edge. This caramelization step is what gives the sauce its depth.
Add spices and tomatoes Add all the sauce spices garam masala, Kashmiri chili, cumin, coriander, turmeric and stir for 30 seconds until fragrant. Pour in crushed tomatoes. Stir to combine, bring to a simmer, and cook uncovered for 10 minutes until the sauce has thickened and darkened.
Add cream Reduce heat to low. Stir in heavy cream. Simmer gently for 5 minutes do not boil after adding cream. Crush kasuri methi between your palms and stir in. Taste and adjust salt. Add sugar if the sauce tastes too acidic.
Add chicken and simmer Add the broiled chicken pieces to the sauce. Stir gently to coat every piece. Simmer for 5 minutes over low heat to allow the chicken to absorb the sauce flavors. The chicken is already cooked this step is about combining flavors, not cooking further.
Serve Spoon chicken tikka masala over basmati rice or serve with warm naan. Garnish with fresh cilantro. Serve immediately with cucumber raita on the side if desired.