In a large pot, bring salted water to a vigorous boil. Add the rigatoni pasta and cook according to package instructions until al dente. Reserve 1 cup of the starchy pasta water, then drain the rigatoni and set it aside in a large bowl.
In a spacious skillet, heat the olive oil over medium heat. Add the Italian sausage, breaking it into smaller pieces with a wooden spoon. Cook the sausage for 5-7 minutes, stirring occasionally, until it’s nicely browned and cooked through.
To the skillet with the sausage, incorporate the chopped onion and minced garlic. Sauté for about 3-4 minutes, or until the onion becomes translucent and aromatic.
Carefully pour in the chicken broth, followed by the heavy cream. Stir thoroughly to blend the ingredients and allow the mixture to come to a gentle simmer.
Add the halved cherry tomatoes, chopped spinach, Italian seasoning, and red pepper flakes (if using). Season with salt and pepper to taste. Allow the mixture to cook for another 5 minutes, until the tomatoes soften and the spinach wilts into the sauce.
Introduce the cooked rigatoni into the skillet, gently tossing it to thoroughly coat in the creamy sauce. If the sauce appears too thick, gradually incorporate reserved pasta water, a little at a time, until the desired consistency is achieved.
Mix in the grated Parmesan cheese, stirring until it melts into the sauce and creates a luscious, creamy texture. Taste the sauce and adjust the seasoning as needed.
Plate the creamy rigatoni into shallow bowls, garnishing with fresh basil leaves for a pop of color and flavor.
Notes
For an elegant touch, serve the rigatoni drizzled with olive oil and additional grated Parmesan on top.