Preheat an oven to 350 degrees F. Rub the chicken all over with the oil, and loosely stuff the cavity with 3 onions, 1 garlic clove and 1 sprig of parsley. Set aside. On the bottom of a 3-quart terra-cotta jug or deep heavy casserole, spread half the proscuitto, 2 sprigs parsley, 4 onions, 1 garlic clove, 1 bay leaf and all of the giblets. Place the chicken head-first in the pot, or breast-side up in a casserole. Scatter the remaining onions, garlic, 3 sprigs parsley, proscuitto and bay leaf around and on top of the chicken. In a small bowl, combine the tomatoes, wine, Port, brandy, mustard, and pepper, and pour over the chicken. Cover the pot or casserole and bake for 1 1/2-2 hours, or until chicken is cooked through.

Remove pot from the oven, and carefully remove the onions and reserve. Drain the liquid from the pot into a large skillet. Lift out the chicken and transfer to a roasting pan fitted with a rack.

Use a slotted spoon to lift out the giblets from the pot, along with any remaining whole onions and add them to the reserved onions.

Set the skillet of liquid over high heat, bring to a boil, reduce to a simmer and cook for 10 minutes, or until liquid is reduced by half, stirring often. Preheat a broiler. Place the chicken under the broiler for 3 to 4 minutes, or until browned. To serve, cut the chicken into pieces and arrange on a large platter. Scatter the onions and giblets around the chicken, and spoon some of the warm sauce over the top. Garnish with parsley sprigs and pass extra sauce