1. Heat the oil in a large pot over a high heat; quickly brown the chicken breasts on all sides, about 30 seconds per side.
2. Remove the browned chicken from the pot and set it aside for a few minutes.
3. Add the chopped onion to the oil and cook it until it starts to soften. Add the chopped garlic and cook for about 2 minutes.
4. Add the flour and mix well until it has soaked up the oil and juices.
5. Put the onion and garlic into a casserole dish and add the chicken. Then add the chopped carrot, celery, bay leaf, thyme and one sprig of parsley. Add the chicken stock and mix well.
6. Cover with a lid and place the casserole dish in a hot oven 200°C /400°F / Gas 6 for approximately 1 hour. Check the juices run clear.
7. Season to taste & sprinkle with chopped parsley. Serve with brown rice or baby boiled potatoes.