Wash & shuck oysters, putting them on the half shell. Saute the mushroom & onion in 1 tbs. Butter until soft but not browned. Add flour & stir to blend. Add milk & stir until thickened. Add oatmeal & stir well. Season to taste w/ salt & pepper. Stir in parsley. Place oysters under broiler for 4 min. Remove & cover each oyster w/ some sauce. Sprinkle w/ Parmesan cheese. Melt 2 tbs. Butter & drizzle a few drops over oysters. Return to broiler & cook for 5 min. Or until browned. This recipe may be made w/ more oysters, depen- ding upon the rest of the dinner planned. It may also be served as a main course.