Preheat oven to 350 °F (175 °C) and grease a 9×13″ baking dish.

Boil rigatoni in salted water until 3–4 minutes before al dente, adding broccoli florets during the last 3 minutes. Drain well.

In the baking dish, combine pasta, broccoli, shredded chicken, Alfredo sauce, garlic powder, salt, and pepper—stir to coat evenly.

Sprinkle mozzarella and Parmesan over the top.

Bake uncovered for 25 minutes, until cheese is melted, bubbly, and golden around edges. Let rest 5 minutes before serving.