Preheat Oven: Set your oven to 375°F (190°C).

Cook Quinoa: In 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.

Sauté Onion and Garlic: In a small skillet, heat olive oil over medium heat. Add diced onion and minced garlic, and sauté until soft and fragrant.

Combine Ingredients: 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.

Assemble Casserole: Transfer the mixture to a greased baking dish. Spread evenly and top with additional cheese if desired.

Bake: Place in the preheated oven and bake for 20-25 minutes, or until the cheese is melted and bubbly.

Serve: Let it cool for a few minutes before serving. This casserole is great on its own or with a side salad.