Best Chicken Noodle soup, hands down.
Make the stock first: Place the chicken and chicken broth in a large stockpot and set it over medium heat. Roughly chop 2 carrots, 2 celery ribs, and 1 onion and add to the broth. Add the peppercorns, garlic, 2 sprigs of parsley, thyme, bay leaf, and enough water to just cover the chicken.
Bring the broth to a boil, reduce heat to a simmer, and cook until the chicken is very tender — about 1 1/4 hours — skimming the surface periodically. Remove the chicken and place in a large bowl. Strain the broth through a very fine sieve into a large, clean bowl or stockpot. Discard the vegetables.
Make the soup next: Skim any fat off the top of the strained broth and discard. Slice the remaining carrots, celery, onions, and leeks into 1/4-inch-thick pieces and set aside. Remove and discard the skin and bones from the chicken, cut meat into 1/2-inch pieces, and set aside. Chop the remaining parsley leaves and set aside.
Melt the butter in a large Dutch oven over medium heat. Add the vegetables and cook until the onions are translucent — about 7 minutes.
Add the chicken, the reserved broth, salt, and pepper. Simmer the soup until the vegetables are tender — about 1 hour. Stir in the egg noodles and parsley and cook until the noodles are tender — about 10 more minutes.
At the end of cooking, stir in zoodles instead of noodles with parsley and cook until heated through, only a few minutes