Grease oblong baking dish; add mushrooms. In saucepan, dissolve bouillon in boiling water. Make paste of flour and small amount of water; add slowly to boullion; blend in parmesan cheese, cream and pepper. Cook over low heat, stirring constantly until thick. Pour over mushrooms. Mix melted butter with stuffing mix and spread over mushrooms. Cover with foil. Bake at 180ºC or 35 minutes.
Remove foil and cook 10 minutes more to brown slightly.