Preheat your oven to 375°F (190°C).

Boil rigatoni in salted water until al dente, drain, and set aside.

Heat olive oil in a large skillet over medium heat.

Add the chopped onion and garlic. Sauté until soft and translucent.

Add the Italian sausage, breaking it up with a spoon, and cook until browned.

Stir in tomato sauce and diced tomatoes.

Add oregano, basil, salt, and pepper. Let simmer for 10 minutes.

Stir in the heavy cream and mix until well combined.

In a large baking dish, combine cooked rigatoni and sausage mixture.

Stir in 1 cup of mozzarella and 1/2 cup of Parmesan cheese.

Top with remaining mozzarella and Parmesan cheese.

Cover dish with foil and bake in the preheated oven for 20 minutes.

Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and golden.

Garnish with fresh basil or parsley, if desired.

Serve hot.