Creating Oven-Baked Chicken Parmesan Casserole is straightforward if you follow these steps:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Prepare Chicken: If necessary, pound the chicken breasts to an even thickness for uniform cooking.
3. Season Chicken: In a bowl, combine salt, pepper, garlic powder, and Italian seasoning. Rub this mixture over both sides of the chicken breasts.
4. Sear Chicken: Heat olive oil in a large skillet over medium-high heat. Sear the chicken breasts for 3-4 minutes on each side until golden brown. Remove from heat.
5. Layer Ingredients: In a 9×13-inch baking dish, spread 1 cup of marinara sauce on the bottom. Place the seared chicken breasts on top in a single layer.
6. Add Sauce and Cheese: Pour the remaining marinara sauce over the chicken. Sprinkle mozzarella and Parmesan cheese evenly on top.
7. Add Breadcrumbs: Sprinkle breadcrumbs over the cheese layer for a crispy topping.
8. Bake: Cover the dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 10 minutes, or until the cheese is melted and bubbling.
9. Garnish: Let the casserole cool for a few minutes before garnishing with fresh basil leaves.
10. Serve: Cut into portions and enjoy your delicious Oven-Baked Chicken Parmesan Casserole.

Following these steps will ensure your casserole turns out perfectly every time.