Preheat the oven to 190°C.
Boil red wine for 10 minutes until reduced by a quarter.
Sauté shallots, celery, and bacon in oil for 5 minutes and set aside.
Coat chicken thighs in seasoned flour and fry until browned on both sides.
Flambé the chicken with brandy and transfer to a casserole pot with vegetables.
Combine stock, tomato purée, garlic, and sugar with the wine and pour over chicken.
Add bouquet garni, cover, and cook in the oven for 50 to 60 minutes.
Sauté mushrooms and onions in butter and add to the casserole for the final 30 minutes.
Whisk in optional beurre manié to thicken the sauce and garnish with parsley before serving.