In a slow cooker, add the chicken breasts, the onions, the carrots, the celery pieces, the thyme, the rosemary, the garlic, the bay leaf, the salt, and the pepper and stir to combine.
Evenly pour the broth over the chicken mixture.
Cover the slow cooker and cook on low heat, about 6-8 hours.
Transfer the chicken breasts to a plate and use two forks to shred the meat.
Remove and discard the thyme sprigs, the rosemary sprig, and the bay leaf from the soup mixture.
Add the shredded chicken and the egg noodles to the soup mixture and stir to combine.
Cover the slow cooker and cook the soup on low heat until the noodles are al dente, about 20-30 minutes.
Serve.
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