For the marinade, mix all of the marinade ingredients together in a bowl until well combined. Add the chicken breasts and make sure theyâ€™re well covered in the marinade. Set aside to marinate in the fridge for 12 hours, or overnight.
when the chicken has marinated, preheat the grill to it's highest setting. Remove the chicken breasts from the marinade, shaking off any excess, and grill for 3-4 minutes on each side, or until the coating is golden-brown. Baste the chicken breasts with the butter and a little lemon juice.
Preheat the oven to 200C/400F/Gas 6 and roast the chicken for 10-12 minutes, or until cooked through.
Meanwhile, for the sauce, heat the butter in a frying pan over a medium heat and fry the onion for 4-5 minutes, or until softened. Add the ginger and garlic and cook for a further minute, then stir in the tomato purÃ©e, chillies and chilli powder and cook for another 2-3 minutes.
Reduce the heat, stir in the cream and simmer for a further minute, then add the chicken breasts to the sauce. Season, to taste, with salt and freshly ground black pepper.
Serve with basmati rice and naan bread.
To serve, place the butter chicken breasts onto serving plates and drizzle over the sauce. Sprinkle over the coriander. Spoon the basmati rice alongside and serve with the naan bread.