Gather all your ingredients and chop the chicken into bite-sized pieces, then set aside.
Mince the garlic and grate the ginger, filling your kitchen with a warm, fragrant aroma.
In a small bowl, mix garlic, ginger, garam masala, cumin, and paprika to create a vibrant spice blend; inhale that warm, smoky scent.
Place the chicken pieces into the slow cooker, then pour in the tomato paste, heavy cream, and add 2 tablespoons of butter. Toss gently to coat everything evenly.
Sprinkle the spice mixture over the chicken, then add the remaining 2 tablespoons of butter on top. Cover and cook on low for 6–8 hours, until the chicken is tender and the sauce is bubbling.
During the last hour, check the sauce— it should be thickening and glossy, with a rich, inviting aroma wafting through the house.
About 15 minutes before serving, stir in lemon juice to add a bright, fresh note to balance the richness.
Uncover the slow cooker, give everything a gentle stir, and taste—adjust salt and pepper if needed.
Serve the butter chicken hot over steamed rice or with warm naan, garnished with fresh herbs if desired. Enjoy the silky, flavorful sauce and tender chicken!