Flamiche aux Poireaux

In a large bowl, combine flour and salt. Add the cold cubed butter and rub quickly between your fingertips until the mixture resembles coarse, pea-sized breadcrumbs — work fast to keep the butter cold. Drizzle in the ice-cold water one tablespoon at a time, mixing with a fork until the dough just comes together without being wet or sticky. Press into a disc, wrap in plastic, and refrigerate for 30 minutes. Roll to a 3 mm circle and line a 24–26 cm tart tin. Prick the base all over with a fork. Refrigerate again for 15 minutes, then blind-bake at 190°C (375°F) lined with parchment and beans for 15 minutes; remove the beans and bake a further 8–10 minutes until the base is pale gold and set.

Wash the sliced leeks thoroughly in cold water and drain well. Melt the butter in a wide pan over low heat. Add the leeks with a pinch of salt and stir to coat. Cook over the lowest possible heat, covered, for 20–25 minutes, stirring occasionally, until the leeks are completely soft, sweet, and yielding — they should have no bite whatsoever. Remove the lid and cook for a further 5 minutes to evaporate any remaining moisture. The leeks should look translucent and silky, not watery.

In a bowl, whisk together the cream, eggs, and half the Gruyère until fully combined. Season generously with salt and white pepper. Fold the cooled stewed leeks into the custard mixture until evenly distributed. The mixture should look creamy and cohesive — not separated.

Pour the leek custard into the blind-baked shell. Scatter the remaining Gruyère evenly across the surface. Place on a baking sheet and bake at 180°C (355°F) for 30–35 minutes, until the custard is just set with only a very slight tremor in the center, the surface is golden, and the cheese has formed patches of deep golden-brown.