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
Kosher salt
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