To the bottom of a 6 quart or larger slow cooker, add trimmed chicken breasts. Top with onion, carrots, celery, garlic, dried thyme, dried rosemary, salt and pepper, and bay leaf if using.
Dollop better than bouillon chicken base over the top, then pour in chicken broth. Gently stir to combine all ingredients thoroughly. Cover the slow cooker and cook on LOW for 6-8 hours or HIGH for 3-4 hours.
Once the cooking time is up, remove chicken from the slow cooker and place it into a large mixing bowl. Shred the chicken using two forks or your hands. Discard the bay leaf if you used one and return the shredded chicken back into the slow cooker.
Now it’s time to add egg noodles to the slow cooker. Stir them in gently so they are well distributed throughout the soup mixture. Cover again and cook on LOW for an additional 10-15 minutes until pasta is tender.
Taste your soup before serving; add salt and pepper as needed. Ladle portions into bowls garnished with minced fresh parsley and a sprinkle of black pepper for added flavor.