Wash your hands well with soap and warm water for at least 20 seconds.
Remove fat from chicken breasts and place chicken in the bottom of a 6-quart or larger slow cooker.
Wash your hands well with soap and warm water for at least 20 seconds.
Wash, peel, and cut carrots into coins (smaller portion) and half moons (larger portion).
Wash celery and cut into small pieces, discard white root ends.
Peel and cut onion into small pieces.
Peel and mince garlic.
Add carrots, celery, onion, garlic, rosemary, thyme, pepper, salt, and bay leaf to the slow cooker on top of the chicken.
Add chicken broth and cook on low for 6 hours or high for 3 hours. Remove chicken and place on a cutting board to cool. Remove bay leaf.
Add noodles to slow cooker and stir ingredients. Cook on low for 15 minutes. While noodles cook, shred chicken with two forks. Add chicken back to slow cooker and stir.