Heat the olive oil in a large pot or Dutch oven over medium-high heat. Add the Italian sausage and cook, breaking it up with a wooden spoon, until browned and cooked through, about 5-7 minutes.
Add the garlic, Italian seasoning, and red pepper flakes and cook for 1-2 minutes, until fragrant.
Add the tomato paste and cook for 1-2 minutes, stirring constantly.
Add the rigatoni, diced tomatoes (do not drain), marinara sauce, and chicken broth. Stir to combine and bring the mixture to a simmer over medium heat. Cover with a lid and cook for 15-20 minutes, stirring every few minutes, until the pasta is cooked al dente and the sauce has reduced and thickened.
When the pasta is cooked, remove the pot from the heat. Stir in the heavy cream and parmesan cheese. Season with salt and pepper, to taste.
Garnish with fresh basil, optional. Serve warm.
Notes
Servings: Serving size is based on 2 ounces of pasta (dry) per person.Storage: Store leftover sausage rigatoni in an airtight container in the refrigerator for 3 to 4 days. Reheat individual portions in the microwave or warm the pasta in a saucepan over low heat, adding a splash of broth or cream if the sauce has thickened.Freezer: Freeze the cooled pasta in a freezer-safe container for up to 3 to 4 months. Thaw overnight in the refrigerator before reheating. The cream sauce may separate slightly after freezing, but stirring while reheating helps bring it back together.