Heat the butter in a pan and add the minced onions. Fry until golden brown
Add the ginger, garlic, coriander powder, chilli powder, turmeric, and salt.
Fry for a minute until fragrant
Add the pureed tomato and tomato paste and cook for 3-4 mins until the mixture bubbles uniformly
Add in the kasuri methi, milk, and the cubed chicken along with some salt
Cook covered for 8-10 mins until the chicken is soft. The chicken will let out more water, just check once or twice in between and give the curry a stir. Keep the heat on low
When the chicken is cooked soft, open the lid and cook for a further minute or two. If the gravy is too thick, add some water at this stage
When done, add the garam masala and the cream or cashew paste. Give it a good stir, but don't boil
Adjust salt, garnish with the coriander leaves, and remove from heat
Serve hot with tawa naan, vegetable pulao, or jeera rice