Gather all your ingredients: trim and cut the chicken into even 2-inch pieces, mince the garlic, and grate the ginger. Measure out the spices and prepare the cream and lemon juice.
In a small bowl, whisk together tomato paste, garam masala, cumin, turmeric, minced garlic, and grated ginger until fragrant and well combined. This spice mixture forms the flavorful base of your sauce.
Place the chicken pieces into the crockpot, then pour the spice mixture over them. Dot the chicken with butter, and add a splash of water or chicken broth to help create a rich sauce during cooking.
Cover and cook on low for 6 to 8 hours until the chicken is tender and shreds easily, and the sauce is fragrant and deeply flavored. During cooking, avoid opening the lid too often to keep the temperature steady.
About 15 minutes before serving, stir in the heavy cream and a squeeze of lemon juice. This will give the sauce a silky texture and a bright, citrusy note. Let it heat through without boiling.
Turn off the crockpot and let the dish rest for a few minutes. Taste and adjust salt or lemon if needed to brighten the flavors. The sauce should be glossy, fragrant, and coat the chicken generously.
Serve hot over steamed rice or warm naan, garnished with freshly chopped cilantro for a vibrant finish. Enjoy the rich, creamy, and aromatic flavors of your slow-cooked butter chicken.
