Toss chicken with melted butter or ghee, spices, salt, and pepper let sit for about 5 minutes.
Place chicken in the crock pot.
Add tomatoes, water, onion, garlic, and garam masala.
Cook on LOW for 8 hours or HIGH for 3.5 hours.
The last 30 minutes, partially uncover and turn to HIGH to allow the sauce to thicken slightly.
Serve over steamed or cauliflower rice.