1. Bring a large pot of salted water to a boil and cook the rigatoni until al dente. Reserve 1/2 cup pasta water, then drain.

2. Heat olive oil in a large skillet over medium heat and cook the Italian sausage until browned, breaking it into small pieces as it cooks.

3. Stir in the minced garlic and chopped sun-dried tomatoes, then cook for 1 to 2 minutes until fragrant.

4. Pour in the heavy cream and chicken broth, then stir in the Parmesan cheese, Italian seasoning, salt, black pepper, and red pepper flakes.

5. Simmer the sauce for 3 to 4 minutes until it starts to thicken.

6. Add the fresh spinach and stir until wilted.

7. Add the cooked rigatoni to the skillet and toss until everything is evenly coated.

8. Add a splash of reserved pasta water if needed to loosen the sauce, then serve hot.