1poundspaghetticook according to package directions
1/2cupshredded Parmesan cheese
2ounces Fontina cheese freshly grated
Melt butter in a 4-quart heavy saucepan over medium heat. Stir in flour and cook for 1 minute. Add milk, salt, and pepper and stir vigorously with wire whip until mixture barely comes to a boil. Reduce heat and simmer 5 minutes, whipping frequently while sauce thickens. Add the Fontina cheese into the sauce, and allow it to melt into the sauce. Keep warm.
Cook bacon thoroughly. Drain on paper towels. Cut into 1/4-inch pieces and stir into sauce. Heat olive oil in large skillet over medium heat. Add sliced mushrooms and minced onions and saute until golden; add to sauce. Cook spaghetti according to the package directions. Drain well and add to the sauce along with the parsley. Blend well and transfer to serving dish. Sprinkle with Parmesan cheese and serve immediately.