Begin by bringing a large pot of salted water to a boil. Add the rigatoni or penne pasta and cook according to package instructions until al dente. Reserve about 1 cup of pasta water, then drain the pasta in a colander and set aside.

In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add the diced onion and sauté until translucent, about 5 minutes.

Add the sausage to the skillet, breaking it apart with a wooden spoon. Cook until browned and cooked through, about 5-7 minutes.

Stir in the minced garlic, dried oregano, and red pepper flakes (if using), and cook for another minute until fragrant.

Pour in the crushed tomatoes and bring to a simmer. Let it simmer for 5 minutes to let the flavors meld.

Reduce the heat and stir in the heavy cream. If the sauce seems too thick, add some reserved pasta water until desired consistency is reached. Season with salt and pepper to taste.

Add the drained pasta to the skillet and toss well to combine, letting it heat through for about 1-2 minutes.

Serve the sausage pasta hot, garnished with fresh basil leaves and grated Parmesan cheese.