Marinade the chicken in the ginger and garlic pastes, salt, chilli powder and lemon juice for an hour. Skewer the chicken pieces and cook in the tandoor till half done. In a large pan cook the onion paste, tomato Purée and chicken stock till it reaches a sauce like consistency. Strain through a muslin cloth. In a kadhai heat 60 gm butter. Add coriander powder and chicken pieces and sauté for 3-4 minutes. Add the sauce and cook for another 3 to 4 minutes. Add sweet ittar and remove to a bowl. Melt the remaining butter in a small pan. Add the green chillies and sauté briefly. Add the cashew nuts and cream and pour onto the dish. Crush saffron in a spoon with a few drops of water and sprinkle over the cashew-cream paste.