Bring 1 quart salted water to a boil in a Dutch oven. Add chicken, and cook 12 minutes or until done. Remove chicken from water with a slotted spoon. Add pasta to water in Dutch oven, and cook 10 minutes or until tender; drain. Keep warm.
Heat 1/4 cup broth over medium-high heat in a Dutch oven; add celery and onion, and cook 5 minutes or until tender. Stir in chicken, soup, cheese, and remaining 3/4 cup chicken broth, stirring until cheese is melted. Toss with pasta; garnish, if desired. Serve immediately.