Marinate the chicken
Combine the yogurt, lemon juice, ginger-garlic paste, chili powder, garam masala, cumin, coriander, turmeric, salt, and oil in a large bowl.
Add the chicken and stir until evenly coated.
Cover and refrigerate for at least 1 hour, or up to 24 hours.
Char the chicken
Position an oven rack about 6 inches from the broiler and set the broiler to high.
Line a baking sheet with foil and set a wire rack on top.
Arrange the chicken in a single layer, shaking off excess marinade.
Broil for 6 to 8 minutes per side, until charred at the edges and the internal temperature reaches 165°F. Set aside.
Build the sauce
Heat the ghee in a large, deep skillet over medium heat.
Cook the onion for 6 to 8 minutes until soft and golden.
Stir in the ginger-garlic paste and cook for 1 minute.
Add the chili powder, garam masala, cumin, and coriander, and stir for 30 seconds.
Pour in the tomato sauce, salt, and sugar. Simmer for 10 to 12 minutes until thick and the oil begins to separate.
Add the water, and blend the sauce with an immersion blender for a smoother texture if desired.
Combine and finish
Reduce the heat to low and stir in the cream.
Add the chicken and any juices from the pan, then simmer gently for 8 to 10 minutes.
Crush the dried fenugreek leaves between your palms and stir them in.
Adjust the salt, garnish with cilantro, and serve hot with rice or naan.