Place the chicken breasts in the crockpot.
Add the carrots, celery, onion, and garlic.
Pour in the chicken broth and add the thyme, parsley, rosemary, salt, pepper, and bay leaf.
Cover and cook on LOW for 6–7 hours or HIGH for 3–4 hours, until the chicken is fully cooked and tender.
Remove the chicken and shred it with two forks.
Return the shredded chicken to the crockpot.
Add the egg noodles during the final 15–25 minutes of cooking.
Cook until the noodles are tender.
Remove the bay leaf and stir in fresh parsley.
Add lemon juice if desired, taste, and adjust the seasoning before serving.