Preheat your oven to 375°F (190°C) and lightly grease a 9×13 baking dish.

Bring a large pot of salted water to a boil, then cook the penne or rigatoni for 2 minutes less than package directions.

Drain the pasta and set it aside so it finishes cooking in the oven.

Heat olive oil in a large skillet over medium-high heat, then add the diced medium yellow onion.

Cook the onion for 3–4 minutes until softened and translucent.

Add the minced garlic and cook for 30 seconds until fragrant.

Add the ground beef and break it apart with a wooden spoon, cooking 6–8 minutes until browned and no pink remains.

Drain excess fat from the skillet.

Stir in crushed tomatoes, tomato paste, beef broth, dried oregano, dried basil, red pepper flakes, salt, black pepper, and sugar (optional), then simmer on medium-low for 10 minutes, stirring occasionally, until the sauce thickens slightly.

In a medium bowl, mix ricotta cheese, egg, 1 cup of shredded mozzarella cheese, grated Parmesan cheese, and fresh parsley, until combined.

Stir the drained pasta into the meat sauce until well coated.

Spoon half the pasta mixture into the prepared 9×13 baking dish.

Dollop the ricotta mixture over the top in spoonfuls.

Add the remaining pasta mixture on top.

Sprinkle the remaining 1/2 cup shredded mozzarella cheese evenly over the top.

Cover tightly with foil and bake for 25 minutes at 375°F (190°C).

Remove the foil and bake an additional 15 minutes at 375°F (190°C) until the cheese is golden and bubbling at the edges.

Let rest for 5 minutes before serving, then garnish with fresh parsley.