How to Make It
Cook pasta according to package directions, omitting salt and fat. Drain.
While pasta cooks, sprinkle chicken with salt and pepper. Melt butter in a large nonstick skillet over medium-high heat. Add chicken, mushrooms, and onion; sauté 7 minutes or until chicken is done. Remove from pan; keep warm.
Add sherry to pan, scraping to loosen browned bits. Stir in broth and cheese; bring to a boil. Reduce heat, and simmer until cheese melts (about 3 minutes), stirring constantly. Return chicken mixture to pan, and cook until thoroughly heated. Serve over pasta.