Creating cheesy baked tortellini is simple when you follow these clear steps:

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Cook the Tortellini: In a large pot, bring salted water to a boil. Add the tortellini and cook according to the package instructions until al dente. Drain and set aside.
3. Mix the Cheeses: In a medium bowl, combine the ricotta cheese, half of the mozzarella cheese, and Parmesan cheese. Mix in the Italian seasoning, garlic powder, salt, and pepper.
4. Combine Tortellini & Sauce: In a large mixing bowl, combine the cooked tortellini with the marinara sauce. Gently fold in the cheese mixture until well combined.
5. Layer in Casserole Dish: Spread half of the tortellini mixture into a greased 9×13-inch baking dish. Sprinkle with half of the remaining mozzarella cheese.
6. Add Remaining Mixture: Pour the remaining tortellini mixture over the cheese layer, and top with the rest of the mozzarella cheese.
7. Bake: Place the baking dish in the preheated oven and bake for about 25-30 minutes, or until the cheese is bubbly and golden.
8. Cool and Serve: Once out of the oven, let the casserole cool for a few minutes. Garnish with fresh basil if desired.