Place chicken into a large pot; cover with water. Add celery leaves. Bring to a boil, then reduce heat and simmer until chicken is cooked through, 30 to 40 minutes. Remove chicken from the pot and place in a bowl until cool enough to handle.

Meanwhile, strain cooking liquid, discard celery leaves, and return cooking liquid to the pot. Place carrots, onion, celery stalks, chicken broth, bouillon, and soup mix into the pot and bring to a simmer over medium heat. Add peppercorns, bay leaves, thyme, poultry seasoning, basil, and parsley.

Bone chicken; cut meat into bite-sized pieces and add to the pot. Simmer until vegetables are tender and flavors are well blended, about 90 minutes.

Stir in pasta; cook until noodles are tender yet firm to the bite, 10 to 15 minutes. Serve hot.