Preheat your oven to 350°F (175°C).
In a large bowl, mix cooked quinoa, chicken, and broccoli.
In a separate bowl, whisk together the cream of chicken soup, milk, garlic powder, salt, and pepper.
Pour the sauce over the quinoa mixture and stir until well combined.
Transfer the mixture to a greased 9x13-inch baking dish.
Top with shredded cheddar and Parmesan cheese.
Bake for 25-30 minutes or until the cheese is melted and bubbly.
Let it cool for 5 minutes before serving.