Spray a 6-quart slow cooker with nonstick cooking spray. Place chicken in the slow cooker and season with salt and pepper.
Pour chicken stock over the chicken then add onion, celery, carrot, thyme, rosemary and bay leaves; stir to combine. Cover and cook on low for 6-8 hours.
After cooking, remove bay leaves and reserve 1 cup of liquid from the slow cooker then shred chicken using two forks.
In a small bowl, whisk together yogurt, milk, flour and reserved broth then stir into the slow cooker. Stir in egg noodles and peas then cover and cook for an additional 30-60 minutes or until pasta is tender and soup has thickened.
Garnish with parsley before serving.