Heat olive oil in a large skillet over medium heat. Add ground beef, salt, and pepper. Cook until browned, breaking it up with a spoon.
Pour in the marinara sauce. Stir and simmer for 5–7 minutes.
Meanwhile, cook tortellini according to package instructions. Drain and set aside.
Add cooked tortellini to the beef sauce. Stir to combine.
Sprinkle mozzarella and Parmesan over the top. Cover with a lid and let the cheese melt, about 2–3 minutes.
Serve warm, garnished with parsley if you like.