Preheat the oven to 375°F (190°C).
In a large skillet over medium heat, brown the ground beef until fully cooked, about 5-7 minutes. Drain any excess fat.
Add the marinara sauce, garlic powder, Italian seasoning, salt, and pepper to the skillet with the ground beef. Stir to combine and let it simmer for another 5 minutes.
While the sauce simmers, bring a pot of salted water to a boil. Cook the tortellini according to package instructions until al dente, about 3-4 minutes. Drain and set aside.
In a large mixing bowl, combine the cooked tortellini with the beef sauce mixture. Stir until the tortellini is fully coated with the sauce.
Transfer the tortellini and beef mixture into a greased 9x13-inch baking dish, spreading it evenly across the dish.
Sprinkle the shredded mozzarella cheese and grated Parmesan cheese evenly over the top.
Bake in the preheated oven for 20 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let cool slightly before serving. Garnish with fresh basil if desired.