Cook the rigatoni pasta according to the package instructions until al dente. Drain and set aside.
Prepare the Sauce:
In a large skillet, heat the olive oil over medium heat. Add the diced onion and minced garlic, and sauté until softened and fragrant.
Cook the Italian Sausage:
Add the Italian sausage to the skillet, breaking it up with a spoon, and cook until browned and cooked through.
Add the Tomato Sauce:
Stir in the tomato puree, salt, pepper, and oregano, and simmer the sauce for 10-15 minutes to allow the flavors to meld together.
Assemble the Pasta Dish:
Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish with olive oil.
In the prepared baking dish, layer half of the cooked rigatoni pasta, followed by half of the tomato sauce mixture, and half of the shredded mozzarella cheese. Repeat the layers.
Bake the Pasta:
Cover the baking dish with aluminum foil and bake in the preheated oven for 20 minutes.
Remove the foil and sprinkle the shredded parmesan cheese over the top of the pasta.
Return the baking dish to the oven and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.
Serve and Enjoy:
Once baked, remove the Pasta al Forno from the oven and let it cool for a few minutes before serving.
Garnish with fresh herbs, such as basil or parsley, if desired
