Marinate the Chicken: In a bowl, combine all the marinade ingredients. Mix well and ensure the chicken is evenly coated. Cover and refrigerate for at least 30 minutes, or up to overnight.

Cook the Chicken: Heat 1 tablespoon of oil or ghee in a large skillet or pot over medium-high heat. Add the marinated chicken in a single layer (you may need to do this in batches) and sear until browned on all sides, but not fully cooked through. Set aside.

Prepare the Sauce: In the same skillet, melt the butter over medium heat. Add the chopped onion and cook until softened and lightly golden, about 5-7 minutes. Add the minced garlic and ginger-garlic paste and cook for another minute until fragrant.

Build the Flavor: Stir in the crushed tomatoes, tomato paste, garam masala, turmeric powder, chili powder, and cayenne pepper (if using). Bring to a simmer and cook for 10-15 minutes, stirring occasionally, allowing the flavors to meld.

Blend the Sauce (Optional): For an extra smooth sauce, use an immersion blender to blend the sauce until smooth. Alternatively, you can carefully transfer the sauce to a regular blender, blend, and then return it to the skillet.

Combine Chicken and Sauce: Add the seared chicken to the sauce. Stir in the sugar (or honey) and season with salt to taste. Simmer for another 10-15 minutes, or until the chicken is cooked through and the sauce has thickened.

Finish with Cream: Stir in the heavy cream and cook for another 2-3 minutes, until heated through. Be careful not to boil the cream.

Garnish and Serve: Garnish with chopped cilantro and serve hot with basmati rice or naan bread.