1. Heat the oil in a large frying pan.
2. Sear the chicken pieces in batches, until nice golden brown on each side. Put in a large ovenproof dish and set aside.
3. Sauté the mushrooms, onion and garlic in the same pan, until soft.
4. Add the stock and vinegar then bring to a boil.
5. Stir in the tomatoes, basil and sugar.
6. Pour the sauce over the chicken, cover with foil and cook for 1 hour in a preheated oven at 180°C.
7. Soak the anchovies in the milk for 5 minutes and drain.
8. After one hour of cooking, take the chicken out of the tin and place on a serving dish.
9. Pour the sauce in a saucepan and bring to the boil for a minute.
10. Reduce the heat to low and stir in the anchovies, olives and parsley. Cook for a minute and pour over the chicken. 

Tip: This dish can be served with pasta or rice according to your preference.