A Tart of Leeks and Cheese

Preheat the oven to 400F (200C).

Bring a large pan of water to a boil.

Peel the potatoes and cut them into slices about 1/8 inch (3mm) thick.

Salt the boiling water, add the potatoes, and let them simmer enthusiastically until tenderthey can be almost falling apart.

Drain and put into a large bowl.

Meanwhile, remove the greenest part of the leeks and discard it.

Slice the white and pale green part into rings, then rinse thoroughly under running water.

Melt the butter in a saucepan and add the leeks.

Cover with a lid and cook over low to medium heat until thoroughly tender; this will take a good twenty minutes.

Put the leeks in with the drained potatoes, then add the creme fraiche and grated Cheddar.

Season with salt, black pepper, and nutmeg.

Roll the pastry into two rectangles approximately 9 1/2 x 12 1/2 inches (24 x 32cm).

Lay one on a nonstick baking sheet.

Pile the filling into the center, then brush the edges with beaten egg.

Lay the second piece of pastry over the top and press the edges down.

Trim around the edges, then pinch firmly to seal.

Brush the top with beaten egg and cut equally spaced slits across the width of the top piece of pastry.

Bake until the pastry is crisp and golden, about forty to forty-five minutes.