Melt butter over medium heat in Dutch oven. Add mushrooms and onion; cook 1 minute, stirring frequently.
Stir in corn starch until blended. Remove from heat. Stir in chicken broth and sherry gradually until smooth. Bring to boil, stirring constantly, over medium heat; boil 1 minute. Remove from heat.
Add parsley and hot pepper sauce. Stir in spaghetti, turkey, Parmesan and red pepper gently. Spoon into ungreased 11 x 7 x 2-inch baking dish.
Bake in 350°F oven 30 minutes or until heated.