Bring a large pot of salted water to a boil. Add the tortellini and cook 2 minutes less than package directions (they’ll finish cooking in the oven). Drain and set aside.
Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish with cooking spray.
Heat the olive oil in a large skillet over medium heat. Add the diced onion and cook for 2–3 minutes, until softened. Add garlic and cook for 1 minute.
Add the ground beef and cook until browned, breaking it up with a spoon.
Stir in the minced garlic powder, dried basil, parsley, oregano, salt, and pepper. Cook for 1–2 more minutes until fragrant.
Pour the marinara sauce into the skillet with the beef mixture and stir to combine. Let the sauce simmer for 2–3 minutes.
Add the cooked tortellini to the baking dish. Pour the beef marinara mixture over the tortellini and stir gently to coat everything evenly. Sprinkle the mozzarella cheese all over the top, followed by the grated Parmesan.
Bake uncovered for 20–25 minutes, or until the cheese is melted, bubbly, and lightly golden.
Remove from the oven and let rest for 5 minutes. Sprinkle with chopped parsley before serving.