Place the onion, 3 diced carrots, 3 diced celery stalks, garlic, whole chicken, 1 teaspoon of the salt, bay leaves, thyme, and parsley into the pressure cooker. Add water to reach the maximum fill line of the pressure cooker, making sure the chicken is mostly submerged.

Seal the lid and cook on High Pressure for 45 minutes.

Allow the pressure to naturally release for 10 minutes, then carefully release any remaining pressure.

Remove the chicken and transfer it to a bowl to cool.

In a large pot, add the remaining diced carrots and celery along with a pinch of salt, to taste.

Pour the broth and cooked vegetables from the pressure cooker through a strainer into the pot with the carrots and celery, pressing the vegetables with the back of a spoon to extract as much liquid as possible.

Simmer for 15 minutes, or until the vegetables are tender.

Remove the skin and bones from the chicken and shred the meat into bite-size pieces. Add the shredded chicken back to the soup.

Season with black pepper and garnish with chopped parsley if desired. Serve as is or with cooked noodles, pasta, or rice.