Heat olive oil over medium heat. Add the carrots, celery, onion, and garlic. Sauté for 5–6 minutes, until softened.
Stir in the Italian seasoning and cook for 1 minute.
Pour in the broth, turkey breast, and add the riced cauliflower. Bring to a boil, then reduce the heat and let simmer for 10-12 minutes.
Add the spinach and simmer 2-3 minutes, until wilted. Let the soup cool slightly before serving.