Melt the butter with the oil in a flameproof casserole. Add the garlic and spring onions (scallions) and fry until they are soft. Add the mushrooms and fry for a further 3 minutes. Transfer the vegetables to a plate.

Add the chicken pieces to the casserole and fry until they are evenly browned. Stir in the seasoning, wine, stock, tomatoes, bay leaf and vegetable mixture, and bring to the boil. Reduce the heat to low, cover and simmer the mixture for 40 to 50 minutes, or until the chicken pieces are cooked through and tender. Remove from the heat and transfer the chicken pieces to a warmed serving dish. Keep hot.

Return the casserole to moderate heat and boil the sauce until it has reduced slightly. Stir in the beurre manie, a little at a time, and cook for a further 2 to 3 minutes, or until the sauce is smooth and fairly thick. Remove from the heat and discard the bay leaf.

Pour the sauce over the chicken, sprinkle over the parsley and serve at once.