Preheat your oven to 375°F (190°C).
Cook the tortellini according to package instructions until al dente. Drain and set aside.
In a large mixing bowl, combine the marinara sauce, ricotta cheese, Italian seasoning, garlic powder, salt, and pepper. Mix until well combined.
Add the cooked tortellini to the sauce mixture and gently stir to coat the pasta evenly.
Transfer the tortellini mixture into a greased 9x13-inch baking dish. Spread it out evenly.
Sprinkle the shredded mozzarella and grated Parmesan cheese evenly over the top.
Bake in the preheated oven for 25-30 minutes, or until the cheese is bubbly and golden brown.
Remove from the oven and let it cool for 5 minutes. Garnish with fresh basil leaves if desired before serving.