Preheat oven to 375°F. Spray a 9×13-inch baking dish with nonstick spray.

Add the uncooked chicken, dry pasta, frozen broccoli, Alfredo sauce, chicken broth, heavy cream, garlic powder, Italian seasoning, salt, and pepper directly to the baking dish. Stir well to evenly combine.

Cover the dish tightly with foil and bake for 40 minutes.

Remove the foil, stir the pasta well, then sprinkle mozzarella and Parmesan evenly over the top. Return to the oven and bake uncovered for 10–15 minutes, until the cheese is melted and bubbly and the pasta is tender.

Let the casserole rest for 5 minutes before serving. Stir gently and enjoy!