Preheat oven to 375°F (190°C) and grease a 9x13-inch baking dish.

Boil the rigatoni in salted water for about 2 minutes less than package directions, until just before al dente. Drain and rinse immediately with cold water to stop cooking and remove surface starch.

In a large skillet over medium-high heat, brown the ground beef with the onion and garlic, breaking up the meat as it cooks. Drain excess fat. Stir in marinara sauce and Italian seasoning, then simmer for 10 minutes.

In a medium bowl, mix ricotta, Parmesan, 1 cup mozzarella, egg, salt, and pepper until smooth. Transfer to a piping bag or zip-top bag with corner snipped.

Spread a thin layer of beef ragu on the bottom of the baking dish. Stand rigatoni noodles upright in the dish, packing them tightly together.

Pipe ricotta mixture into each standing noodle from the top. Spoon remaining ragu over the tops of the stuffed noodles, letting sauce drip into the gaps.

Sprinkle remaining 1 cup mozzarella over the top. Cover with foil and bake for 20 minutes. Remove foil and bake for another 10 to 15 minutes until cheese is bubbly and lightly browned.

Let rest for 5 minutes before serving. Garnish with fresh basil or parsley.