Place the chicken breasts at the bottom of the crockpot.
Add the chopped onion, carrots, and celery on top of the chicken.
Stir in the minced garlic and thyme.
Pour the chicken broth over the ingredients.
Season with salt and pepper to taste.
Cover and cook on low for 6-8 hours or high for 3-4 hours.
Remove the chicken and shred it with two forks.
Return the shredded chicken to the crockpot.
Stir in the egg noodles, cover, and cook for an additional 30 minutes on high.
Garnish with fresh parsley before serving.