Beat all the marinade ingredients together in a shallow dish.
Add the chicken to the yoghurt mixture. Cover and refrigerate for at least 2 hours or up to 12 hours ahead of time.
Wash the rice thoroughly, then leave it to soak in a generous amount of lukewarm water for 30 minutes. Swish it around with your fingers every now and then to loosen the starch. Strain the rice, rinsing it again with warm water.
Bring 2.5 litres of water to the boil in a large saucepan. Add the salt and stir in the strained rice. Return the water to a roiling boil and cook, uncovered, for 5 minutes. Test the rice by pinching a grain between your fingers or by biting it. It should be soft on the outside, but still hard in the centre.
Strain the rice and rinse again with warm water. Toss it several times to drain away as much of the water as you can.
Preheat the oven to 190 C and butter a 2 litre ovenproof dish.
Remove the chicken pieces from the yoghurt marinade. Mix half of the parboiled rice with the marinade and spoon it into the base of the ovenproof dish. Spread the rice over the bottom and up the sides of the dish.
Arrange the chicken on top of the rice, then spoon the rest of the rice to cover, and smooth the surface. Cover tightly with a sheet of lightly buttered foil and bake for 1.5 hours.
Remove the dish from the oven and dot the surface of the rice with bits of butter. Replace the foil and leave to rest for 10 minutes.
Turn the rice out onto a warm serving platter.
Serve with a bowl of creamy yoghurt and a selection of fresh herbs – tarragon, basil, chives and parsley would be lovely.