For marinating: The process can go through two marination steps, but I just did one.
Take a bowl, add in the chopped chicken pieces. You can choose to go for chicken with bone as this dish can be boneless or with bone. Add ginger paste, garlic paste, garam masala, chicken masala, red chilli powder, salt and lemon juice. Mix well and set it aside for 20-30minutes. I set it aside for 1 hour, you can leave it overnight too (in the fridge 😉)

To make the tandoor chicken:
After marination, take a frying pan. Pour in some oil enough to fry the chicken but not too much. Place the chicken pieces in the pan and turn them to the other side when you think it might have cooked for quite some time (may be about 7 minutes). Use low flame. Keep turning them until they are brownish (light brown). Once ready, take the pieces out into a bowl.

Use the same frying pan, add in cardamon pods, cinnamon sticks, cloves, curry leaves and sauté. Add ginger garlic paste. Once you start smelling the garlic, add in the onions. Let it fry for some minutes, all using medium flame. Add in the chopped tomatoes, green chillis and butter, you can add tomato puree too. Add garam masala, chilli powder, chicken masala, salt, cashew nuts and water. Mix, cover and let it cook for about 20 minutes. After 20 minutes, let it cool.

Pour the mixture in step 3 into a grinder and grind. Once it's all mixed and ground, sieve it in order to get rid of the coarse spices and tomato skin/seeds. Also remember butter chicken gravy has to be velvety smooth. You can use a hand grinder too but a mixer grinder is the best choice.

Add butter 😁to the same frying pan. Add some garlic paste. I used grated garlic (last minute 😁). Pour in the liquid puree and let it cook for about 20minutes. Add in the tandoor chicken pieces, sugar, coriander leaves and salt if it's not as per your taste yet. Sprinkle in fenugreek, and add in thick cream. Stir and let it cook for another 10 minutes