In a large pot, bring salted water to a rolling boil over high heat. Add the penne pasta, cooking until al dente, which should take about 10 minutes. Stir occasionally to prevent sticking. Once done, drain the pasta and set it aside, reserving a small amount of the cooking water for later use.

While the pasta cooks, heat a large skillet over medium heat and drizzle in olive oil. Once shimmering, add the Italian sausage, breaking it up with a wooden spoon. Brown the sausage for 5-7 minutes until fully cooked and no longer pink.

Next, add diced onion and minced garlic to the skillet with the sausage. Sauté until the onion becomes translucent, about 3-4 minutes.

Stir in the diced tomatoes along with their juices, heavy cream, and Italian seasoning. Allow the sauce to simmer for 5 minutes.

Lower the heat and gently fold the cooked penne pasta into the creamy sauce. Stir in the shredded mozzarella and half of the grated Parmesan cheese, mixing until melted.

Taste your dish and season with salt and pepper according to your preference. Serve hot, garnished with the remaining Parmesan cheese and freshly chopped basil if desired.