Preheat oven to 375 degrees Fahrenheit (190 degrees Celsius) and lightly grease a 9x13 inch baking dish.
Boil a large pot of salted water and cook tortellini 2 minutes less than the package instructions for al dente; drain and set aside.
In a large skillet over medium-high heat, brown the ground beef until no pink remains, then drain excess fat.
Add the diced onion to the skillet and sauté for 5 minutes until translucent, then add the minced garlic and cook for 1 minute.
Stir in the marinara sauce, oregano, and basil, allowing the mixture to simmer for 5 minutes.
In the prepared baking dish, combine the cooked tortellini and the meat sauce, stirring until the pasta is evenly coated.
Spread the shredded mozzarella and Parmesan cheese evenly over the top.
Bake for 20 minutes or until the cheese is melted and the sauce is bubbling around the edges.
Remove from oven and let rest for 5 minutes before serving.