Until last week I thought Cod au gratin had to be a French dish, served in places I couldn't afford to go, even in France. On top of that I thought that "au gratin" meant "grated cheese", (gratin=grated, right?

I have since looked up a few recipes.
Au Gratin seems to be whatever food you plan to make, with a cheese sauce poured over it, the lot topped with breadcrumbs, and the casserole baked in an oven.
This recipe for cod au gratin is titled "A Newfoundland Favourite" and it comes from Rock Recipes, "rock" as in "The Rock". (Which, of course, sends me off trying to anagramize "au gratin" with "granite")
So now, of course, I shall embark on a few weeks of cooking everything au gratin, a great excuse to buy cheese and eat up everything in sight: potatoes, fish, red meat, artichokes, cabbage, ...
And since I experiment with bread recipes I have a near-endless supply of bread crumbs(grin)
Cheers, Chris