Pour 32 ounces low-sodium chicken stock into a large pot and heat over high heat until it comes to a boil. Reduce heat to maintain a gentle simmer.
Add the 2 peeled, chopped carrots, 1 chopped stalk celery, the thinly sliced white and light green parts of 1 leek, the 2 large bone-in chicken breasts or thighs, and 2 teaspoons Vegit. Stir to combine.
Simmer, uncovered, for about 25 minutes, or until the chicken is cooked through and the vegetables are tender (internal temperature of the chicken should reach 165°F or the meat is no longer pink).
Use tongs or a slotted spoon to remove the chicken from the pot and place it on a plate. Allow it to cool until you can handle it comfortably (a few minutes).
Remove and discard the bones and any skin, then tear or chop the chicken into bite-size pieces.
Add the cooked 1 cup egg noodles (or cooked pasta) and the shredded/chopped chicken back into the simmering broth. Heat just until everything is warmed through, about 2–3 minutes.
Serve the soup hot.