In a large pot, bring 4 quarts of water to a boil.Preheat crockpot for 10 minutes on high heat. Add the chicken, garlic, rosemary and broth to the crockpot. Cook for 45 minutes or until the chicken is fully cooked through.Remove chicken and shred with a fork and place back in crockpot. Add the celery and carrots and cook for an additional 15 min.
Once the pot of water comes to a boil, add 3 tbsp of salt.Add the pasta and cook for 10 minutes. Drain pasta and add to crock pot.
Sprinkle grated parmesan cheese. (optional)