Heat oil; sear breast halves 5 min; set aside.
Sauté half the onions 2–3 min; transfer to bowl.
Brown chicken pieces in batches 4–5 min each; return with onions; cover and sweat 20 min.
Add boiling water, breasts, salt, and bay leaves; simmer 20 min; remove, shred, strain, and skim fat.
Sauté remaining onions, carrots, and celery in reserved fat 5 min; add thyme, broth, and chicken; simmer 10–15 min.
Stir in egg noodles; cook 5 min; season and stir in parsley; serve.