Set your oven to 375°F (190°C).
n a medium saucepan, combine quinoa with water or chicken broth. Bring to a boil, then reduce heat to low, cover, and simmer for 15-20 minutes, or until all liquid is absorbed and quinoa is fluffy.
In a small skillet, heat olive oil over medium heat. Add diced onion, carrots, and minced garlic, and sauté until soft and fragrant.
In a large bowl, mix the cooked quinoa, cooked chicken, steamed broccoli, cream of chicken soup, shredded cheese, milk, sautéed onion and garlic, salt, pepper, and paprika if using.
Transfer the mixture to a greased baking dish. Spread evenly and top with additional cheese if desired.
Place in the preheated oven and bake for 20-25 minutes, or until the cheese is melted and bubbly.
Let it cool for a few minutes before serving. This casserole is great on its own or with a side salad.