Cheesy Broccoli Quinoa Casserole

uncooked quinoa (I love Ancient Harvest)

water or low sodium broth (for cooking quinoa)

bags of frozen broccoli florets*

olive oil

large yellow onion, chopped

garlic, minced

block of good quality cheddar cheese

mushroom soup (not condensed), store-bought or homemade

sea salt,

ground pepper,