Gather your equipment: a large slow cooker, a sharp knife, a cutting board, a ladle, and a measuring cup. Make sure the slow cooker is clean and ready to go.
Prepare the chicken: trim any excess fat from the chicken breasts and cut them into large, roughly 2-inch chunks. This helps them cook evenly and stay tender.
Chop the vegetables: peel and dice the carrots, dice the celery stalks, and dice the onion into small, uniform pieces. These will cook down to add flavor and texture to the soup.
Place the chicken, carrots, celery, onion, minced garlic, dried thyme, and a pinch of salt and pepper into the slow cooker. This forms the flavor base of your soup.
Pour in the chicken broth, covering the ingredients. Give everything a gentle stir to combine, then cover with the lid.
Set your slow cooker to low and cook for 6 to 8 hours, or on high for 3 to 4 hours. The house will fill with a savory aroma as the chicken becomes tender and flavors meld.
About 30 minutes before serving, add the wide egg noodles to the slow cooker. Stir gently to distribute, then cover and cook on high. Check after 15 minutes—noodles should be tender but still have a slight bite.
Test a noodle for doneness; if it’s tender but not mushy, stir in chopped fresh parsley and squeeze in a little lemon for brightness. Adjust seasoning with salt and pepper if needed.
Turn off the slow cooker and let the soup rest for 5 minutes. This helps the flavors settle and thickens the broth slightly.
Use a ladle to serve the soup into bowls, making sure each portion has a good mix of chicken, vegetables, noodles, and broth. Garnish with extra parsley if desired, and enjoy your comforting bowl of homemade chicken noodle soup.
