Cook the linguini according to package instructions (omitting the salt).
Drain and keep warm.
In a large frying pan, melt the butter over medium heat.
Add the mushrooms and celery, sauté until tender.
Stir in the cornstarch and mix well.
Stir in the chicken broth, white wine, lemon juice, thyme and red pepper sauce.
Cook, stirring constantly, until bubbly.
Reduce heat and add the Mozzarella, stirring constantly just until the cheese melts.
Stir in the chicken and spinach.
Simmer, covered, for 1 minute or until mixture is hot.
Serve immediately over the hot cooked linguini.
Sprinkle with the Parmesan cheese.