Preheat your oven to 375°F (190°C). This ensures the casserole cooks evenly throughout.

In a large skillet over medium heat, add a splash of olive oil. Season the chicken pieces with salt, pepper, and garlic powder.

Add the seasoned chicken to the skillet and cook for about 5-7 minutes, stirring occasionally, until the chicken is browned and cooked through. This step adds flavor and ensures the chicken is tender.

Remove the chicken from the skillet and set aside.

In the same skillet, add the marinara sauce, dried oregano, and dried basil. Stir to combine and let it simmer for about 5 minutes. This allows the flavors to meld together.

In a large mixing bowl, combine the cooked pasta, cooked chicken, and marinara sauce. Mix well to ensure everything is evenly coated.

Transfer the mixture to a 9x13 inch baking dish, spreading it out evenly.

In a separate bowl, combine the beaten egg and bread crumbs. This mixture will create a crispy topping.

Sprinkle the bread crumb mixture evenly over the chicken and pasta mixture in the baking dish.

Top with shredded mozzarella and grated Parmesan cheese, ensuring an even layer for a cheesy crust.

Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes. This helps to keep the casserole moist.

After 25 minutes, remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden brown.

Remove from the oven and let it cool for 5-10 minutes before serving. This allows the casserole to set, making it easier to serve.