1. Heat a large pot over medium heat and add olive oil. Brown the Italian sausage, breaking it up as it cooks. Once fully cooked and slightly crispy, remove it with a slotted spoon and set aside.

2. In the same pot, add more olive oil if needed. Sauté onion, carrots, and celery for 5-7 minutes until soft. Add garlic and cook for 1 minute more.

3. Pour in chicken broth and crushed tomatoes. Deglaze the pot by scraping up any browned bits. Return sausage to the pot.

4. Add cannellini beans, fresh herbs, and red pepper flakes. Bring to a boil, then reduce to a simmer and cook uncovered for 20-25 minutes.

5. Stir in chopped kale or spinach and let it wilt for about 5 minutes.

6. Season with salt and pepper to taste. Ladle into bowls, garnish if desired, and serve hot.