Place the chicken thighs, chicken broth, chopped carrots, chopped celery, chopped onion, minced garlic, dried thyme, dried parsley, black pepper, kosher salt, and bay leaves into the bowl of a 6-quart or larger slow cooker.
Stir all the ingredients gently to combine them, ensuring the chicken is fully submerged in the broth.
Cover the slow cooker with its lid and cook on the LOW setting for 6 to 7 hours, or until the chicken is extremely tender and shreds easily with a fork.
Carefully remove the chicken thighs from the soup and place them on a clean cutting board. Use two forks to shred the meat into bite-sized pieces, then return all the shredded chicken to the slow cooker.
Add the 3 cups of uncooked egg noodles to the slow cooker, stir to submerge them in the hot broth, cover, and cook on the HIGH setting for an additional 20 to 30 minutes, or until the noodles are tender.
Turn off the slow cooker, discard the bay leaves, and taste the soup. Adjust seasoning with additional salt and pepper if desired. Ladle the soup into bowls and garnish with the fresh chopped parsley before serving.