In a large heavy bottomed pot over medium heat, add in the ghee and stir until melted.
Add in the chopped onion, garlic and ginger.
Sauté, stirring occasionally until the onions soften.
Add in the paprika, Kashmiri chili powder, turmeric, coriander, cumin, cayenne (if using) and dried fenugreek, toasting the spices with the aromatics until they release their fragrance, about 1 minute.
Add in the sea salt, sugar, tomato sauce/passata and tomato paste.
Bring to a simmer and cook uncovered until the sauce thickens, about 15-20 minutes.
Transfer the sauce to a high-powered blender (or use an immersion stick blender) to blend the sauce until smooth.
Return the sauce to the pot and heat to a simmer.
Transfer the cut, charboiled chicken into the sauce cook for another 10-12 minutes, until chicken is fully cooked through.
Finish with heavy cream and remove from heat.
Garnish with chopped cilantro.
Serve with steamed basmati rice or naan.