Preheat oven to 350°F (175°C).
Boil the pasta in salted water until 3-4 minutes under al dente.
Add the chopped broccoli to the boiling pasta water and cook until pasta is al dente.
Drain the pasta and broccoli, then transfer to a 9×13-inch baking dish.
Add shredded chicken, Alfredo sauce, salt, pepper, and garlic powder to the dish.
Mix until evenly combined, then top with Parmesan and mozzarella cheese.
Bake uncovered for 25 minutes, until the cheese is melted and bubbly.
Let it cool slightly before serving.