There are two steps required for the preparation of chicken butter tikka masala.
Marinate the chicken with all the ingredients and mix well so that the chicken pieces are coated well with the masala(while cleaning the chicken, please drain out any extra water).
Keep the marinated chicken in the fridge for at least 1 to 2 hours.
Melt butter on a flat pan and spread all the chicken one by one on the pan. After few minutes, flip the chicken pieces. The chicken will be done as soon as you see a very slight brown color. The butter should be used enough to saute the chicken.
Take another pan and add some oil or butter. To this add garlic paste and fry for few seconds and then add ginger paste and fry for few seconds.
Add onions paste which is should be very fine paste/puree. Fry till this mixture till it is light brown. Then add all the spices(chilly powder, paneer tikka masala and garam masala) and fry till nice aroma comes. We need to make sure that the masala does not burn, so once we add the spices, immediately turn the burner to low flame.
Grind the tomato and cashew in a blender or magic bullet. Add this tomato and cashew nut paste and fry for few minutes till all the gravy is combined well. At this point if the gravy is too thick, add water to get the required consistency. Add salt to taste.
Lastly, add the chicken and boil for few minutes till the chicken is fully cooked.
Turn the burner to very low flame and add heavy cream. Mix well.
Add one pinch of Kasoori Methi and coriander leaves with few drops of butter for garnishing. Chicken butter tikka masala is ready.
1)We can prepare the chicken curry in advance and add the cream just few minutes before serving to get more fresh taste.