Follow these steps to prepare a delicious Italian Sausage Soup:

1. Cook the Sausage: In a large pot or Dutch oven, heat olive oil over medium heat. Add the Italian sausage, breaking it up with a spoon, and cook until browned and cooked through, about 5-7 minutes. Remove the sausage with a slotted spoon and set aside, leaving the rendered fat in the pot.​

2. Sauté Aromatics and Vegetables: In the same pot, add the diced onion, sliced carrots, and chopped celery. Sauté until the vegetables are softened, approximately 5 minutes. Add the minced garlic and cook for an additional minute until fragrant.

3. Add Tomatoes and Broth: Pour in the diced tomatoes with their juices, chicken broth, and water. Stir in the dried basil, dried oregano, and crushed red pepper flakes if using. Bring the mixture to a boil.​

4. Incorporate Beans and Sausage: Once boiling, add the cannellini beans and the cooked sausage back into the pot. Reduce the heat to a simmer and let it cook for about 10 minutes to allow the flavors to meld.​

5. Cook the Pasta: Stir in the uncooked ditalini pasta and continue to simmer until the pasta is al dente, following the package instructions (usually 8-10 minutes).​

6. Add Spinach and Season: In the last few minutes of cooking, add the chopped fresh spinach and stir until wilted. Taste the soup and season with salt and freshly ground black pepper as needed.​

7. Serve: Ladle the soup into bowls and garnish with grated Parmesan cheese. Serve hot with crusty bread for a complete meal.