Add the ginger, garlic and green chilli in a wet grinder and blend to a smooth paste. Mix the yoghurt with the gram flour in a bowl to get rid of any lumps to form a thick paste like consistency. Add the ginger, garlic chilli paste, paprika, chilli powder, garam masala and coriander powder. Also mix in the ground cinnamon, saffron and salt. Stir well and tip in the chicken pieces and mix well making sure to coat them in the thick marinade. Leave to marinate for a few hours or even overnight if you prefer.