Prepare the Ingredients: Start by removing the casings from the Italian sausage and dice the onion, carrots, and celery. Mince the garlic and chop the spinach or kale if using.

Cook the Sausage: In a large pot, heat 1 tablespoon of olive oil over medium heat. Add the Italian sausage and cook, breaking it apart with a spoon until browned and fully cooked. This should take about 5-7 minutes. Once cooked, remove the sausage from the pot and set it aside.

Sauté the Vegetables: In the same pot, add the diced onion, carrots, celery, and garlic. Sauté for 5-6 minutes until the vegetables are softened and the onion is translucent.

Add the Broth: Pour in the chicken broth and bring the mixture to a simmer. Add the browned sausage back to the pot, along with the dried Italian seasoning, salt, black pepper, and crushed red pepper flakes if you like a spicier soup.

Simmer the Soup: Let the soup simmer for about 15-20 minutes, allowing all the flavors to meld together. Check that the carrots and celery are tender.

Add the Cream and Spinach/Kale: Reduce the heat to low and stir in the heavy cream, grated Parmesan cheese, and spinach or kale. Stir well until the cheese melts and the greens are wilted, about 2-3 minutes.

Taste and Adjust Seasoning: Taste the soup and add more salt, pepper, or red pepper flakes if desired. Serve hot with additional grated Parmesan if you like.