In a large pot, heat the olive oil over medium heat. Add the diced chicken and cook until browned, about 5-7 minutes. Remove the chicken from the pot and set aside.
In the same pot, add the chopped onion, carrots, and celery. Sauté for about 5 minutes, or until the vegetables begin to soften. Add the minced garlic and sauté for an additional minute until fragrant.
Pour in the chicken broth and bring to a boil. Add the diced tomatoes (with their juice), cooked chicken, Italian seasoning, and red pepper flakes if using.
Reduce the heat to a simmer, cover the pot, and cook for 15-20 minutes.
Stir in the chopped kale or Swiss chard and cannellini beans. Cook for another 5 minutes until the greens are wilted and tender.
Season the soup with salt and pepper to taste.
Serve hot, garnished with fresh basil leaves and a sprinkle of grated Parmesan cheese.
Notes
Feel free to adjust the vegetables based on your preference.