Heat olive oil in a large stockpot over medium heat.
Add diced onion, carrots, and celery to the pot and sauté for 8 minutes until vegetables begin to soften.
Add minced garlic and cook for 60 seconds until aromatic.
Pour in chicken stock and add dried thyme and the bay leaf.
Place the chicken breasts into the liquid, bring to a gentle boil, then reduce heat to low and simmer for 25 minutes.
Remove the chicken breasts from the pot and shred into bite-sized pieces using two forks.
Return the shredded chicken to the pot and season with salt and black pepper.
Simmer for an additional 5 minutes to integrate flavors.
Remove the bay leaf and stir in fresh parsley before serving.