The Best Chicken Tikka Masala

Name: The Best Chicken Tikka Masala
Prep time: 15 min
Cook time: 40 min
Total time: 55 min
Cuisine: Indian, British
Ingredients: 5 pounds bone-in chicken pieces (breasts, legs, or a mix), skin removed; 3 tablespoons toasted ground cumin; 3 tablespoons toasted paprika; 2 tablespoon toasted ground coriander seed; 2 teaspoon ground turmeric; 1 teaspoon cayenne pepper; 12 cloves garlic, grated on the medium holes of a box grater, divided; 3 tablespoons fresh ginger, grated on the medium holes of a box grater, divided; 2 cups yogurt; 3/4 cup fresh juice from 4 to 6 lemons, divided; Diamond Crystal kosher salt; for table salt, use about half as much by volume; 4 tablespoons butter or ghee; 1 large onion, thinly sliced; 1 (28-ounce) can whole peeled tomatoes, roughly mashed; 1/2 cup roughly chopped cilantro leaves and tender stems; 1 cup heavy cream