Special equipment:
7in (18cm) springform pan

Ingredients:
4 tbsp unsalted butter
2 tbsp olive oil, plus extra for greasing
1lb 2oz (500g) leeks, washed, trimmed,
and finely shredded
sea salt and freshly ground black pepper
nutmeg
2 tbsp all-purpose flour, plus extra for dusting
1 cup milk
4oz (100g) blue cheese, such as Stilton (optional)
1lb 2oz (500g) store-bought puff pastry,
or 1 quantity puff pastry, see page 178, steps 1–9
1 large egg, beaten

Method:
1 Preheat the oven to 400°F (200°C). In a large saucepan, melt the butter and olive oil. Add the leeks and cook over low heat for 10 minutes, stirring occasionally, until well softened but not browned. Season well with salt, pepper, and a little grated nutmeg. Scatter the flour over the surface of the leeks and stir it in well.

2 Pour the milk onto the leeks, a little at a time, stirring constantly. The mixture will thicken to begin with, then gradually loosen as all the milk is added. Bring to a boil, reduce the heat, and cook for 3–5 minutes, until well thickened. Remove from the heat and stir in the cheese (if using).

3 Roll out the puff pastry on a well floured work surface into an 8 x 16in (20 x 40cm) rectangle. It should be 1⁄8–¼in (3–5mm) thick. Place the pan onto one short edge of the pastry and cut a circle around it to make the lid; the remaining pastry should be large enough to line the bottom of the pan.

4 Oil the pan, trim the remaining pastry, anduse it to line the pan, allowing the sides to overhang slightly. Brush the interior with a little beaten egg and set aside for 5 minutes; this may seem unusual, but the dried egg wash creates a kind of lacquer that prevents the pastry from going soggy.

5 Fill the pastry crust with the leek mixture and brush a little beaten egg around the edges of the pastry. Top with the disk of pastry and press around the edges to seal together. Brush the top of the flamiche with beaten egg, then cut 2 small slits in the top to allow the steam to escape.

6 Bake in the top third of the oven for 25–30 minutes, until puffed up and golden brown. Remove the flamiche from the oven, trim the excess pastry, and cool for at least 10 minutes before serving warm or cold.

PREPARE AHEAD:
The flamiche will keep overnight, covered, and chilled in the refrigerator. Gently reheat, or bring back to room temperature, before eating.

BAKER’S TIP:
A flamiche is traditionally decorated by scoring a crisscross pattern of lines over the top of the uncooked pastry. In my experience, however, such overlapping lines can cause the pastry to split. I simply use a very sharp knife to draw lines coming out of the center, like the spokes of a wheel.

Flamiche Recipe