Preheat oven to 425. Place butter in 9 x 13 baking dish and place in oven as it preheats. Place chicken pieces in zip top bag. Add flour and shake to coat. When oven is warm, remove pan from oven and place the floured chicken in pan with the melted butter. Return to oven and cook for 30 minutes. Turn the chicken and continue cooking for 20 min. While the chicken bakes, chop onion. Saute' onion in a small skillet with a little olive oil. Chop mushrooms and add them to the onion. Saute' until the onions are becoming transparent and the mushrooms are heated through. Set aside. In a medium bowl, add can of soup, milk, pepper and cheese. Combine with a spatula. Add cooked onion and mushrooms to the soup mixture and combine. Set aside until chicken is done. When the chicken is done, reduce oven temp to 325. Drain off excess fat or remove chicken and place in a clean baking dish. Pour soup mixture over chicken. Sprinkle paprika on top. Cover securely with foil and bake for 20 minutes. Serve with rice or egg noodles and a green salad.