In a large heavy-bottom skillet, heat 3 tbsp of cooking oil to medium.
Add the onions and fry for 10-12 minutes until they turn golden brown.
Add garlic and ginger and fry for 20-30 seconds for the aromas to release.
Add all ground spices and stir to combine.
Immediately add chopped tomatoes or passata.
Give it all another good stir, lower the heat and simmer the sauce for 10-12 minutes. Stir occasionally, scraping the bits off the sides of the pan.
Once the sauce thickens and becomes fragrant, add a cup of water, cover and continue to simmer for another 15 minutes. (this would be the good time to send the chicken into the oven!)
Add 200ml of cooking cream (reserve just a little for garnish!), 1 tbsp sugar and 1 tbsp fenugereek leaves, if using, and stir in the chicken tikka.
Simmer for the last 2-3 minutes.
Serve drizzled with a little more cream, garnished with fresh cilantro leaves, with a side of white rice or paratha/naan.