Place the hen in a large stock pot.
Cut each carrot and celery stalk into 3 large chunks and place on top of the hen.
Cut the onion into large chunks and place on top of the carrots and celery.
Place the wrapped parsley and bay leaves on top of the vegetables.
Fill two steel diffusers (or a tea ball) with black peppercorns and star anise and place in the stock pot. This doesn't have to be an accurate measurement, just fill it up. If you don't have diffusers, just pop them into the pot with the vegetables and make sure to strain the vegetables later.
Pour the box of chicken broth over top of everything in the stock pot.
Fill the rest of the pot up with water, until all the ingredients are just covered.
Bring the pot to a boil over high heat and then turn down to medium/low and cover and simmer for the whole day (or at least 8 hours).
Once the stock is done simmering, remove the chicken and place onto a plate. Skim any little floaty bits off the top of the stock, then strain it into another pot to remove the veggies (optional).
Shred the chicken and set aside, then discard the carcass and bones.
Taste the stock to see if it needs any additional salt, or any additional chicken broth.
Gently press out any excess moisture from the zoodles with a paper towel and then divide them between bowls. Ladle stock over top and add shredded chicken.