In a medium saucepan, combine the quinoa and vegetable broth. Bring to a boil, then reduce heat to low, cover, and simmer for about 15 minutes, or until the quinoa is cooked and the liquid is absorbed.
In a large mixing bowl, combine the cooked quinoa, artichoke hearts, spinach, mozzarella cheese, Parmesan cheese, garlic powder, salt, and black pepper. Mix well.
Transfer the mixture to a greased baking dish. Spread it out evenly.
Bake in the preheated oven for 20-25 minutes, or until the top is golden and the casserole is heated through.
Let it cool for a few minutes before serving.
Notes:
This casserole is great for meal prep and can be stored in the fridge for up to 4 days.