Creating the Hearty High Protein Chicken Parmesan Casserole is straightforward. Follow these steps to make this incredible dish:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Cook Chicken: In a skillet, heat olive oil over medium heat. Add the diced chicken and season with garlic powder, Italian seasoning, salt, and pepper. Cook until the chicken is no longer pink and is cooked through, about 6-8 minutes.
3. Combine Ingredients: In a large bowl, combine the cooked chicken, marinara sauce, cooked quinoa or brown rice, and chopped spinach. Mix well until all ingredients are evenly coated.
4. Transfer to Baking Dish: Pour the mixture into a greased 9×13-inch baking dish, spreading it evenly.
5. Add Cheese: Sprinkle the shredded mozzarella cheese and grated Parmesan cheese evenly over the top of the casserole.
6. Bake: Place in the preheated oven and bake for 30-35 minutes, or until the cheese is melted and bubbly.
7. Garnish: Remove from the oven and let it cool for a few minutes. Garnish with fresh basil, if desired.
8. Serve: Cut into squares and serve warm.

By following these simple steps, you’ll create a delicious and satisfying casserole that everyone will enjoy!