Preheat oven to 375°F.
In a large bowl or baking dish, stir together quinoa, 1 ½ cups cheese, chicken, black beans, corn and bbq sauce until combined. Transfer the quinoa mixture to a baking dish (or leave it, if you’re mixing this up in the baking dish), and sprinkle the remaining ½ cup cheese evenly on top.
Bake for 15-20 minutes, or until the cheese is melted and the casserole is warmed through. Remove from the oven, and drizzle the top of the casserole with a little extra bbq sauce, and top with your desired (optional) garnishes.
Serve immediately.