Preheat your oven to 375°F (190°C).
In a large mixing bowl, combine the marinara sauce, ricotta cheese, Italian seasoning, garlic powder, salt, and pepper. Mix well until smooth.
In a greased 9x13-inch baking dish, spread a thin layer of the sauce mixture on the bottom.
Layer half of the frozen ravioli over the sauce in the baking dish.
Spread half of the remaining sauce mixture over the ravioli, then sprinkle with half of the mozzarella cheese and half of the Parmesan cheese.
Repeat the layers with the remaining ravioli, sauce mixture, mozzarella, and Parmesan cheese.
Cover the baking dish with aluminum foil and bake for 25 minutes.
Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden brown.
Let the casserole cool for 5-10 minutes before serving. Garnish with fresh basil leaves if desired.