1. Heat 1 tablespoon of coconut or olive oil in a large skillet over medium-high heat. Add diced onion, ginger paste, and minced garlic. Sauté for 3–6 minutes until onions are golden and fragrant.

2. Add smoked paprika, cumin, turmeric, garam masala, salt, and optional red pepper flakes and sugar. Toast spices for 1–2 minutes, stirring constantly.

3. Add the canned tomatoes to the skillet. Stir well and simmer for 1–2 minutes. Remove from heat and let cool briefly.

4. Place trimmed chicken thighs in a 6-quart Crockpot. Pour the tomato-spice mixture over the chicken and stir to coat.

5. Cover and cook on High for 2½ to 4 hours or Low for 4 to 6 hours, until chicken is fork-tender and reaches 165°F internally.

6. Remove chicken and set aside. Blend the sauce in the Crockpot using an immersion blender or transfer to a stand blender until smooth. Return blended sauce to Crockpot.

7. Stir in butter and heavy cream until melted and fully combined into a velvety sauce.

8. Chop the cooked chicken into bite-sized pieces and return to the sauce. Stir in chopped cilantro if using. Let everything warm together for 10–15 minutes on Low.

9. Serve hot over basmati or jasmine rice with warm naan. Garnish with additional cilantro if desired.