Cook Rigatoni: Begin by bringing a large pot of salted water to a boil. Add 8 oz of rigatoni pasta and cook according to package instructions until al dente, approximately 8-10 minutes. Drain and set aside.
Prepare the Beef Sauce: In a skillet, heat 1 tbsp of olive oil over medium heat. Add 1/2 cup of diced onion and sauté for about 2 minutes until translucent. Then, add in 2 cloves of minced garlic and sauté for another minute. Next, add 1 lb of ground beef, seasoning with salt, pepper, and 1 tsp of Italian seasoning. Cook until the beef is browned, about 7-10 minutes, breaking it apart with a spatula.
Combine with Sauce: Once the beef is nicely browned, pour in 1 jar (24 oz) of marinara sauce. Stir to mix well and let it simmer for 5-7 minutes, allowing the flavors to meld.
Assemble the Dish: Preheat your oven broiler if you’re using it. In a large baking dish, mix the cooked rigatoni with the beef sauce until well combined.
Top with Cheese: Generously sprinkle 1 cup of shredded mozzarella cheese and 1/4 cup of grated Parmesan cheese over the top of the mixture. Broil for 2-3 minutes until the cheese is bubbly and golden brown, being careful to watch closely so it doesn't burn.
Serve: Allow the dish to cool slightly, then plate and enjoy your delicious rigatoni while it's hot!