In a large bowl, combine the yogurt, lemon juice, 2 teaspoons ground cumin, cinnamon, 1 teaspoon Kashmiri chili powder, tandoori masala, 2 teaspoons black pepper, 1 tablespoon minced ginger, 2 cloves minced garlic and 1 teaspoon salt.
Add the chicken pieces to the marinade and toss to coat evenly. Cover and refrigerate for at least 1 hour or overnight for best flavor.
Preheat your grill or broiler. Thread the marinated chicken onto skewers, discard excess marinade, and grill or broil, turning occasionally, until cooked through, about 10–15 minutes. Remove and set aside.
Heat 2 tablespoons butter in a large skillet over medium heat. Add 1 clove minced garlic and sauté briefly until fragrant.
Add ½ teaspoon Kashmiri chili powder, 2 teaspoons ground cumin, 2 teaspoons paprika and 1 teaspoon garam masala to the skillet and toast for about 30 seconds, stirring constantly.
Pour in the 8 ounces tomato sauce (or passata), stir, and cook for 2 minutes, stirring frequently.
Stir in 1 cup heavy cream and reduce heat to low. Simmer the sauce until it thickens slightly, about 20 minutes, stirring occasionally.
Add the grilled chicken to the sauce and simmer for 10 more minutes. Season with additional salt to taste.
Garnish with chopped fresh cilantro and serve with cooked rice or warm naan bread.