Flamiche aux Poireaux

Flamiche is an old northern word, from the Flemish vlaamsche meaning roughly "Flemish" or "flat cake", and once described any savory tart of the Picardy, Hainaut and Flanders plains. The leek version is the one most associated today with Picardy and the Nord, leeks being a winter mainstay of the cold, damp north. Like its cousin the Maroilles tart and the Belgian goyère, it grew out of farmhouse and bakery cooking, using a baker's bread dough or a short pastry and whatever the garden gave. It remains a plain regional standard rather than a restaurant dish.

The filling is soft and creamy, the leeks reduced to a sweet, silky tangle with almost no bite left, mild and faintly oniony, lifted only by salt, pepper and sometimes a touch of nutmeg. The custard sets just firm enough to slice, and the pastry holds a thin crisp edge against the soft centre. There is nothing aggressive about it — no cheese tang, no smoke — just the round sweetness of slow-cooked leeks and butter. Warm, with a green salad, it is comfort food of the plainest, most satisfying kind.

Everything turns on stewing the leeks gently and long. Sweated in butter over low heat — sometimes with a splash of water, lid on, in what the French call à l'étuvée — the leeks soften and their sharp sulphur compounds mellow, while slow cooking draws out their natural sugars, so the filling tastes sweet rather than raw and oniony. The egg-and-cream custard coagulates in the oven to bind the leeks into a sliceable set without going rubbery, which depends on a moderate temperature. Blind-baking or a thin pastry keeps the base from going soggy under the wet filling.