Preheat the oven to 350°F (175°C).
In a large mixing bowl, combine the cooked chicken, marinara sauce, ricotta cheese, half of the mozzarella cheese, half of the Parmesan cheese, cooked pasta, Italian seasoning, minced garlic, salt, and pepper. Stir well to combine all the ingredients.
Grease a 9x13 inch baking dish with olive oil to prevent sticking.
Pour the chicken mixture into the prepared baking dish, spreading it evenly.
Top with the remaining mozzarella and Parmesan cheese.
Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.
After 30 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 a few minutes before slicing. Garnish with fresh basil leaves if desired.