What au gratin means
Au gratin is a French phrase that describes food finished with a browned, crisp topping. The word gratin comes from the French gratter, to scrape, and originally referred to the crust that formed in the cooking dish. Today, a dish served au gratin is usually covered with grated cheese, breadcrumbs, butter or a combination, then baked in a hot oven or placed under a hot grill until the top is golden, crisp and bubbling. The dish underneath is often bound with a sauce, such as béchamel, cheese sauce or cream.
Common examples include potatoes au gratin, cauliflower au gratin, macaroni au gratin, leeks au gratin and seafood au gratin. In Britain, cauliflower cheese is a familiar example of the style. In the US, the phrase is used especially for sliced potatoes baked with cream and cheese, often as a side dish. Shallow, wide dishes are best for cooking au gratin, because they give a large surface for the topping to brown.
Cooked ingredients can be finished quickly under a grill, while raw ingredients need longer in the oven before browning. The phrase is closely related to gratin, the dish itself, and gratinée, another French description. You will see au gratin on menus and in recipes for side dishes, pasta bakes and vegetables.