Melt 4 tablespoons butter; blend in flour and seasonings. Add milk and 1 cup broth; cook until thick and smooth. Stir in cheese. Saute onion, green pepper, and celery in remaining butter. Add 1-cup broth; simmer for 5 minutes. Add to sauce with noodles and chicken. Turn into a casserole dish. Bake at 350 degrees for 30 minutes.