Preheat oven to 180C/350°F Pour the stock into a saucepan and add the lemon grass and half the kaffir lime leaves. Bring to the boil and simmer, covered for ten minutes.
Heat the oil in an oven proof casserole dish and add the onion cooking until soft but not coloured. Add the curry paste and cook for another minute. Add the rice and stir until coated. Strain the stock into the rice and add the coconut cream. Cover and bake for 15 minutes.
Remove from the oven, stir well and add the chicken. If dry add another 1/2 cup of stock or water. Bake for another 30 minutes until the chicken is cooked and the rice tender.