Preheat the oven to 375°F (190°C) and lightly grease a 9x13-inch baking dish.
In a large bowl, season the cubed chicken breast with garlic powder, Italian seasoning, red pepper flakes, salt, and pepper.
Spread the seasoned chicken cubes in an even layer across the bottom of the prepared baking dish.
Pour the marinara sauce evenly over the chicken, ensuring all pieces are covered.
Distribute the shredded mozzarella cheese and grated parmesan cheese evenly over the sauce layer.
Sprinkle the panko breadcrumbs over the top of the cheese.
Bake for 30 to 35 minutes until the chicken reaches an internal temperature of 165°F and the cheese is melted and golden.
Allow to rest for 5 minutes before garnishing with fresh herbs and serving.