Heat olive oil in a large pot over medium heat and add the chopped onion. Cook until soft and slightly translucent, then stir in the garlic. Let it cook briefly until fragrant without burning.
Sprinkle in red pepper flakes and mix well to release their flavor. Pour in the crushed tomatoes and stir to combine everything. Let it simmer for a few minutes to deepen the taste.
Pour in the broth and bring the mixture to a gentle boil. Add the rigatoni directly into the pot and stir well so the pasta is evenly coated. This method allows the pasta to absorb all the flavors.
Reduce heat to medium-low and let the pasta cook uncovered. Stir occasionally to prevent sticking and ensure even cooking. The pasta will soften and the sauce will thicken naturally.
Once the pasta is tender, pour in the heavy cream and stir thoroughly. Add grated Parmesan cheese and mix until melted and smooth. Season with salt and pepper as needed.
Turn off the heat and let the pasta rest for a couple of minutes. Garnish with fresh basil if desired. Serve warm and enjoy the creamy, spicy goodness.