Rub the chicken pieces with some salt, red chili powder, ginger and garlic paste. Keep this aside for 15 minutes
Meanwhile, place the chopped tomatoes, onions, ginger, garlic and chilis in your cooking pot with ½ cup water and cook over medium flame. Once the tomatoes soften (in around 15 minutes) along with the onions, turn the flame off and let it cool
Then run this, along with the cashews, in a grinder to make a smooth paste. Strain this mixture in a bowl and discard the tomato peels and seeds - this ensures a smooth curry
Heat the cooking pot with 2 tablespoons butter and the oil and sauteé the chicken pieces, until completely cooked. Set these aside
In the same pan, add the strained tomato-onion puree´, butter, tomato paste, salt and sugar, mix well and cook this for about 5-7 minutes
Add the cooked chicken pieces, the cream, chili powder, garam masala and the kasuri methi. Simmer over medium low flame for another 7-10 minutes
Garnish the yummy one pot butter chicken with some more fresh cream and kasuri methi and serve hot with naan and/or rice. Enjoy!