In a large pot, heat the extra virgin olive oil over medium heat.
Add the diced yellow onion, sliced carrots, and sliced celery, sautéing for 5 minutes until the onions are translucent.
Stir in the minced garlic and dried oregano, cooking for one minute until fragrant.
Place the whole chicken breast into the pot and pour in the chicken broth.
Bring the liquid to a boil, then reduce the heat to low and simmer for 15 minutes or until the chicken is fully cooked through.
Carefully remove the chicken breast from the pot, shred it using two forks, and return the shredded meat to the soup.
Add the diced zucchini and rinsed cannellini beans to the pot, simmering for another 8 minutes until the zucchini is tender.
Stir in the fresh baby spinach and lemon juice, allowing the spinach to wilt in the residual heat.
Season with sea salt and black pepper before serving hot.