Place the chicken breasts in the bottom of the slow cooker.
Add the diced onion, minced garlic, diced carrots, and diced celery on top of the chicken.
Pour in the chicken broth and water.
Sprinkle the dried thyme, dried parsley, ground black pepper, and salt over the ingredients in the slow cooker.
Cover and cook on low for 3.5 hours, until the chicken is cooked through and vegetables are tender.
Remove the chicken breasts from the slow cooker and shred them using two forks.
Return the shredded chicken to the slow cooker.
Add the frozen corn kernels and egg noodles to the slow cooker. Stir to combine.
Cover and cook on high for an additional 30 minutes, or until the noodles are tender.
Stir in the fresh lemon juice and chopped fresh parsley.
Taste and adjust seasoning with additional salt and pepper if desired.
Serve the soup hot.