Cook the Sausage:

Heat the olive oil in a large pot over medium heat. Add the Italian sausage and cook until browned, breaking it apart as it cooks. Remove and set aside.

Sauté the Vegetables:

In the same pot, add the diced onion and cook for 5 minutes until softened. Stir in the garlic, Italian seasoning, and red pepper flakes (if using). Cook for 1 minute until fragrant.

Add the Broth and Tomatoes:

Pour in the chicken broth and diced tomatoes. Bring to a simmer, then stir in the pasta. Cook according to the package instructions until the pasta is tender.

Finish the Soup:

Lower the heat and stir in the cooked sausage, heavy cream, Parmesan cheese, and spinach. Season with salt and pepper to taste. Simmer for a few minutes until the spinach wilts and the soup thickens slightly.

Serve:

Ladle the soup into bowls and enjoy with extra Parmesan on top!