Completely de-bone turkey thighs with a de-boning knife. To do so, make an incision along thigh bone to open up the thigh. Work knife around joints on either side. I prefer to run my fingers along the bones to separate the bone from the meat.
In a food processor, blend all marinade ingredients other than the yogurt and turkey thigh meat. Add blended mix to mixing bowl, then add yogurt and mix together with ingredients from food processor.
Cut turkey thighs into approximate 1 inch cubes and add to mixing bowl with yogurt and spices. Thoroughly mix and cover with plastic wrap. Place in fridge to marinate for 36-48 hours.
When ready to cook, in a large (preferably cast-iron) skillet heated on medium-low, add a thin layer of sunflower oil, followed by chopped onion. Lightly salt and pepper. Once onions start to brown, add tablespoon of unsalted butter and stir in, picking up any brown bits from the onions.
Add 1½ tablespoons freshly chopped garlic and 1 tablespoon freshly chopped ginger. Stir and allow to cook for couple minutes, then add 21 ounces crushed tomatoes (can and a half), 2 cups chicken stock, and for spices: ½ teaspoon cumin, 1½ teaspoons garam masala, 1 teaspoon ground coriander, ½ teaspoon chili powder, 1 tablespoon brown sugar, and 1 teaspoon each of kosher salt and ground black pepper. Stir and allow to simmer for 10 minutes.
Add liquid mix to food processor and blend thoroughly (still no cream). Leave in food processor and using the same skillet, add turkey thigh chunks to skillet. No need to rinse or shake off yogurt marinade. Turn heat to medium high.
Do not crowd skillet, which will likely mean adding only 6-8 pieces at a time when cooking. Overcrowding will cause the meat to steam and prevent adequate sear. Also, turkey gives off a lot of moisture when cooking, so after browning all sides, set chunks aside on a plate and drain liquids from skillet. Repeat until all chunks are seared.
Add liquids from the food processor back to skillet and reduce heat to medium-low. Add all seared meat turkey thigh chunks back into skillet.
Allow to simmer for 2½ hours. Stir often. Add more chicken stock if liquid starts to appear too dry or does not cover meat entirely. After 2½ hours, add 1 cup heavy whipping cream and allow sauce to reduce for 45 minutes to 1 hour.
In a medium covered saucepan, bring rice and water to a boil then reduce to low until water evaporates. Turn off burner once water evaporates.
Once sauce is thick and the meat is tender, salt sauce to taste. Plate rice and ladle over sauce. Optional: Garnish with finely minced fresh cilantro and pair with naan bread.