Heat olive oil in a large pot over medium heat.
Add onion and garlic, and sauté until the onion is translucent, about 5 minutes.
Stir in the carrots, celery, and red bell pepper. Cook for another 5 minutes until the vegetables begin to soften.
Add the thyme, oregano, and red pepper flakes, stirring to combine.
Pour in the chicken broth and diced tomatoes. Bring to a simmer.
Add the shredded chicken and cannellini beans. Season with salt and pepper to taste.
Let the stew simmer for 20-25 minutes, allowing the flavors to meld together.
Stir in the fresh spinach and cook until wilted, about 2 minutes.
Remove from heat and stir in the fresh basil.
Ladle into bowls and top with freshly grated Parmesan cheese before serving.