In a large stock pot, add chicken bones/skin and onion scraps. Cover with water until stock pot is almost full, about 12-16 cups. Bring to a boil, reduce heat, and simmer for at least 2 hours and up to 12 hours. Remove bones and skin and strain the broth to remove everything else but the liquid. Set aside.
In the empty stock pot, melt the chicken fat or butter on medium heat. Add onions and saute until soft and translucent.
Add potatoes, frozen vegetables, chicken, and chicken broth. Stir in Italian seasoning and pepper. Bring to a boil and cook for 6 minutes. Add egg noodles and continue cooking until cooked through and potatoes are tender, about 6-8 minutes more or as directed on the noodle packaging.
Serve and enjoy!