Preheat the 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 cooked tortellini, marinara sauce, Italian seasoning, garlic powder, salt, and pepper. Mix well.

In a greased baking dish, layer half of the tortellini mixture. Sprinkle half of the mozzarella and half of the Parmesan cheese on top. Repeat with the remaining tortellini and cheeses.

Cover the baking dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and golden.

Remove from the oven and let it cool for a few minutes. Garnish with fresh basil before serving.