Mix the yoghurt with the other marinade ingredients
Place the chicken in a large freezer bag and spoon the yoghurt over the chicken and into its cavity.
Leave for at least two hours but ideally overnight, in the fridge turning occasionally.
Mix the butter with the spices, garlic and ginger
Preheat the oven to 200 degrees C
Remove the chicken and leave to sit at room temperature for about 45 minute
Remove the chicken from the marinade and wipe off the excess
Carefully make a pocket underneath the skin of the breast by slipping your fingers in between the skin and the flesh and loosen the skin over the legs and thighs.
Spread the masala butter underneath the skin, down over the legs, thighs and breast on both sides
Spread the remaining butter on top of the skin and sprinkle with sea salt and place on a roasting tray.
Roast the chicken for one hour and 10 minutes, basting with the butter a few times
Cover the chicken lightly with foil if it browns too dark
When it is cooked, the juices between the leg and the rest of the bird should run clear, with no trace of pink
Cover the bird with a double layer of foil and leave to rest for 15 minutes before serving with the cooking juices
Serve with roast potatoes, plain yoghurt, fresh coriander and naan bread