Cook spaghetti for 10 minutes as instructed on box; rinse with cold water and drain. In electric oven, sauté mushrooms and onion in butter. Add ham cubes and cook a little longer. Add soup, milk and seasonings. Simmer on low for 35 to 40 minutes. One-half hour before serving, add cooked spaghetti and Parmesan cheese. If mixture becomes too dry, add cooked spaghetti and Parmesan cheese. If mixture becomes too dry, a little more milk can be added. Mix thoroughly and keep on low heat. Serves 6 to 8.