Boil the noodles according to the package directions.
While the noodles are cooking, fry the sausage into small pieces with the mushrooms and Italian seasoning. Drain the excess grease.
Add the spaghetti sauce to the sausage mixture.
Drain the cooked noodles and combine them with the sausage mixture.
Transfer to a covered casserole dish and bake at 350 degrees for 10 minutes.
Top with the mozzarella cheese and bake for another 10 minutes, or until the cheese is melted.
Let stand for 5 minutes before serving.