Bring a large pot of generously salted water to a boil. Add the rigatoni and cook according to package directions until al dente. Before draining, reserve about 1 cup of the pasta water, then drain the pasta in a colander.

While the pasta cooks, heat the olive oil in a large skillet or Dutch oven over medium-high heat. Add the Italian sausage and cook, breaking it apart with a wooden spoon, until it's browned and cooked through, about 5-7 minutes. Do not drain the fat.

Add the diced yellow onion to the skillet with the sausage. Sauté for 4-5 minutes until the onion has softened and become translucent. Stir in the minced garlic and red pepper flakes and cook for another minute until fragrant.

If using, pour in the red wine to deglaze the pan, scraping up any browned bits from the bottom of the skillet. Let it simmer and reduce for about 2 minutes.

Stir in the crushed tomatoes, dried oregano, a pinch of salt, and a few grinds of black pepper. Bring the sauce to a simmer, then reduce the heat to low, cover, and let it gently simmer for at least 10-15 minutes to allow the flavors to meld.

Reduce the heat to the lowest setting and slowly stir in the heavy cream and the 1/2 cup of grated Parmesan cheese. Continue stirring gently until the cheese is fully melted and the sauce is smooth and creamy. Taste and adjust seasoning with more salt and pepper if needed.

Add the drained rigatoni to the skillet with the sauce. Toss well to coat every piece of pasta. If the sauce seems too thick, add a splash of the reserved pasta water until it reaches your desired consistency.

Remove from heat and stir in the fresh basil. Serve immediately, topped with additional grated Parmesan cheese.