Prep the veggies: Slice carrots and celery, dice the onion, and mince the garlic. Keep them in evenly sized pieces so they cook at the same rate.
Optional sauté: For deeper flavor, sauté the onion, carrots, and celery in olive oil or butter for 5–6 minutes until softened. Add garlic and cook 30 seconds.
Transfer to the crock pot.
Load the crock pot: Add vegetables, chicken, broth, bay leaves, thyme, parsley, rosemary, and a pinch of salt and pepper.
Slow cook: Cover and cook on Low for 6–7 hours or on High for 3–4 hours, until the chicken is tender and easily shreds.
Shred the chicken: Remove chicken to a plate. Discard skin and bones if using bone-in. Shred meat with two forks and return it to the crock pot.
Add noodles: Stir in egg noodles.
Cook on High for 15–20 minutes, or until noodles are just tender. Check early; overcooked noodles turn mushy.
Finish and season: Stir in lemon juice if using. Taste and adjust with salt and pepper.
Remove bay leaves.
Serve: Ladle into bowls and top with fresh parsley. Add a splash of extra hot broth if you prefer it soupier.