Ficelle Picarde

The ficelle picarde — Picard for 'Picardy string', after the thin rolled shape of the crêpe — is a 20th-century creation, not a peasant dish: it is generally credited to chef Marcel Lefèvre of the Hôtel du Commerce in Amiens, who served it in 1950 at the Foire-Exposition de la Hotoie, a regional fair where a meal was laid on for the department's notables. (English-language references attribute it more cautiously to 'a chef at the Hôtel du Commerce', and dismiss as unhistorical the legends that trace it to the court of Louis XIV.) Its heart, though, is much older: the mushroom duxelles. That preparation of finely chopped mushrooms and shallots was named in the 17th century for Nicolas Chalon du Blé, marquis d'Uxelles, by his cook François Pierre de La Varenne, whose Le Cuisinier françois (1651) is regarded as the first modern French cookbook. Today the ficelle is an emblem of Amiens and the wider Hauts-de-France.

A soft, creamy bundle under a thin gratinéed crust. The crêpe goes silky and almost melts into the sauce; inside, the mushroom duxelles is dark, savoury and concentrated, set against the salt of the ham, with the cream binding it all and the browned cheese giving a faint nutty edge on top. It should be unctuous, not soupy — the duxelles dry enough to hold, the sauce thick enough to coat rather than pool, the crust golden but not scorched. Eaten hot from the dish, often with a green salad to cut the richness.

Three things make it work. First the duxelles: mushrooms are about 90% water, so chopping them fine and cooking them down hard drives off that moisture and concentrates the savoury, glutamate-rich flavour into a dry, dark paste — undercook it and the released water thins the filling and makes the crêpe soggy. Second the sauce: the authentic version, defended by the local confrérie, uses thick crème fraîche rather than béchamel, but where béchamel is used it is a roux (butter and flour cooked together) loosened with milk, where the flour's starch granules swell and gelatinise to thicken; the cream or sauce must be heated gently, not boiled hard, or the acidity and high heat can split it into oily flecks. Third the gratin: under the oven's top heat the cheese melts and its proteins and milk sugars brown through the Maillard reaction and a little caramelisation, building the golden, faintly nutty crust and the aroma that defines the dish.