Leek and creme fraiche tart

Nigel Slater, Sainsbury's magazine. Serves 8. 14 steps

pastry							Sprinkle leeks in pastry case, pour in custard, sprinkle with parmesan. Bake in moderate oven 25 minutes or until the custard is just set. It should still woblle slightly when moved.
200g plain flour			rub with fingertips until it resembles fine breadcrumbs	Roll out and place into buttered and floured pastry tin, without stretching. Fill in any holes, trim the overhanging edges, and refrigerate 20 minutes.	Bake blind, lined with foil and beans, in moderately hot oven 15 minutes. Remove foil and beans, and bake a further 5 minutes, or until pastry surface is dry to the touch.
100g butter	cut into small pieces
pinch salt
1 large egg's yolk			add and make a firm ball
little cold water
filling
25g butter						melt
200g leeks	Cut in half then into thin slices; wash thoroughly in cold running water; shake dry					add, cover, steam over low heat 10–12 minutes or until softened a little and bright green; make sure they do not brown
2 large eggs		whisk
100g creme fraiche		whisk in
100ml milk
salt and pepper		season
25g parmesan	grate finely

Nigel Slater is very particular about how to make the crust. You should put a baking sheet in the oven to heat it up beforehand. You should use a metal tart tin with a loose bottom.