In a large pot or deep skillet, heat a drizzle of olive oil over medium heat. Add the Italian sausage, breaking it up with a wooden spoon, and sauté for about 5–7 minutes until browned and cooked through. Toss in the diced onion, and allow it to soften and turn translucent, which takes about another 3–4 minutes.

Once the onion is tender, stir in the minced garlic and sauté for about 1 minute until fragrant. Be careful not to burn it.

Pour in the crushed tomatoes and heavy cream, stirring gently to combine. Sprinkle in the dried Italian herbs and red chili flakes if desired. Let this mixture come to a simmer for about 5–10 minutes.

While the sauce simmers, bring a large pot of salted water to a boil. Add the rigatoni and cook until al dente, about 10–12 minutes. Drain the pasta, reserving some cooking water.

Add the drained rigatoni directly into the creamy sauce. Toss well to coat, adding reserved pasta water if the sauce is too thick.

Serve hot, garnished with freshly grated Parmesan cheese and optional fresh basil.