This tart from the Picardie region of northern France features leeks in a creamy sauce encased in puff pastry (pâte feuilletée) — and yes, it’s fine to use store-bought pastry. In fact that’s what I do myself. If you prefer to make the dough yourself, which is a bit of a production, there are many recipes available online. Here’s a good one.
The leeks are simmered to tenderness in butter, then cream is added. For best results try to find crème fraîche, as its slightly sour flavor enhances the sauce. If crème fraîche is not available, then substitute heavy cream and add 1/2 tsp. of freshly squeezed lemon juice.
The tart makes a fine main dish for lunch or a light supper dish. In winter, I’d suggest starting with soup, for example butternut soup or celeriac soup. Or you could start with the tart and follow up with a salad. The tart may also be served as the starter for a more elaborate meal. It would pair well with a fruity red wine.
The quantities below will fill a 9-inch (23-cm) tart pan and will serve four people as a main dish or six as a starter. If you’d like to make a larger tart, double the quantity of leeks, butter, cream and salt. This would make eight generous servings.
4 sturdy leeks
4 tbsp. (50 g) unsalted butter
1 cup (250 g) crème fraîche
1 tsp. salt
freshly ground black pepper
freshly grated nutmeg
2 tsp. water
2 sheets (packets) puff pastry (pâte feuilletée)
a little extra butter for buttering the pan
Cut off and discard the bottoms and the dark green tops of the leeks. Cut each leek in half crosswise, then lengthwise. Wash the leeks by plunging them into a large pot of cold water. Rinse well to remove any sand, then drain through a colander. Now chop the clean leeks crosswise to make pieces about 1/2 inch (1 cm) wide.
Melt the butter in a large skillet. Add the leeks and sauté, stirring occasionally, until they have wilted and are tender, about 5 minutes. Do not let them brown.
Add the cream, stir well to blend, and simmer for about 5 minutes more to allow the cream to thicken slightly. While the leeks are simmering, add the salt, grind on a generous dose of black pepper and grate some nutmeg over the leeks. Stir to blend.
Set aside for at least half an hour to allow the leeks to cool to room temperature.
When ready to resume, preheat the oven to gas mark 7 (400 F, 210 C).
Crack the egg, placing the yolk in a small bowl and discarding the white. Add 2 tsp. water to the yolk. Mix will to blend. This will be your glaze.
Butter a 9-inch (23-cm) tart or cake pan. Unroll a pastry sheet and center it over the pan. Press the dough onto the bottom and sides of the pan, allowing the extra to hang over the sides. Prick the bottom with a fork.
Transfer the cooled leeks into the tart pan, distributing evenly.
Now unroll the second sheet of pastry and lay it over the pan. Pinch the two layers of dough overhanging the pan together.
Using a scissors, cut around the extra dough to leave a border about 2/3 inch (2 cm) wide. Roll up the border to form a scroll around the pan. Pinch it as though fluting a pie.
Using a sharp knife, make crisscross patterns in the dough and cut away a small circle of dough in the center – this is both for decoration and to allow steam to escape.
Using a pastry brush, paint the top of the tart, including the border, with your glaze.
Bake for 10 minutes, then turn down the heat to gas mark 6 (350 F, 180 C) and continue baking for 20 minutes more, or until the tart is golden brown.
Allow to rest briefly. If serving later, reheat in a low oven for about 10 minutes.
Serve hot or warm. Serves 4-6.