In a large skillet, cook sausage and onion over medium heat until meat is no longer pink; drain. Stir in mushrooms; cook for 1 minute. Add 1 cup broth, Worcestershire sauce and pepper; cover and simmer for 5 minutes or until heated through.
In a small bowl, combine remaining broth and flour; stir until smooth. Gradually stir into skillet. Bring to a boil; boil and stir for 2 minutes. Reduce heat; add sour cream. Stir until heated through (do not boil). Add parsley if desired. Serve with noodles.