Preheat your oven to 375°F (190°C).
Cut the chicken into bite-sized pieces.
In a large baking dish, combine the uncooked penne pasta, chicken pieces, marinara sauce, and water. Add in the Italian seasoning, garlic powder, salt, and black pepper. Stir everything together until well mixed.
Cover the baking dish tightly with aluminum foil and bake for 30 minutes.
Remove the foil, stir gently, sprinkle the mozzarella and Parmesan cheese on top, and bake uncovered for an additional 15-20 minutes until the cheese is bubbly and golden.
Let it sit for 5 minutes before serving.