This mushroom and quinoa casserole is a hearty and nutritious dish that is perfect for vegetarians and meat-lovers alike. The earthy flavor of mushrooms pairs beautifully with the nutty taste of quinoa, creating a delicious and satisfying combination. The mushrooms are sautéed with onions and garlic until golden and then mixed with cooked quinoa. A creamy sauce made with vegetable broth, milk, and Parmesan cheese is poured over the mushroom and quinoa mixture. The casserole is then baked until the top is golden and the flavors have melded together. Serve this casserole as a main course or as a side dish for a wholesome and flavorful meal.