Wash and trim mushrooms and cut in half. In large casserole dish, combine chicken, mushrooms, whole garlic cloves, wine and dressing. Cover and marinate in refrigerator overnight. Remove chicken and mushrooms and measure 2 cups of marinade. Pour remaining marinade into another container. Return chicken and mushrooms to casserole. Mix 2 cups marinade with cans of gravy and pour over chicken. Bake at 325 degrees for 1 1/2 hours. Serve hot over rice, potatoes or biscuits. Note 1: Remaining marinade can be frozen for later use as marinade for barbeque.