Preheat your oven to 375°F (190°C).
In a medium mixing bowl, combine the ricotta cheese, Italian seasoning, garlic powder, salt, and black pepper. Mix until smooth.
In a large saucepan over medium heat, warm the marinara sauce until heated through.
Spread a thin layer of marinara sauce on the bottom of the baking dish (about 1 cup).
Layer half of the ravioli over the sauce, placing them evenly across the dish.
Spread half of the ricotta mixture over the ravioli.
Sprinkle with 1 cup of shredded mozzarella cheese and ½ cup of grated Parmesan cheese.
Repeat with another layer of marinara sauce, the remaining ravioli, the remaining ricotta mixture, and finish with the remaining marinara sauce.
Top the casserole with the remaining mozzarella and Parmesan cheeses.
Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.
Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and slightly golden.
Let the casserole cool for about 5-10 minutes before serving. Garnish with fresh basil leaves if desired.