Put butter, flour, and icing sugar in a food processor. Process until mixture resembles breadcrumbs. Add yolks and water and process until mixture begins to form a ball.

Turn onto a lightly floured surface and knead until smooth. Cut the dough in half, wrap pieces in plastic and refridgerate 15 minutes.

Preheat oven ton(180º)c rool dough until 3mm thick. Line pie plate. For top pastrey, gather pastry scraps without excess flour, knead to form a ball and roll out again

Brush pastry edges withbeaten egg crimp closed. Sprinkle with sugar. Bake for 20-25 minutes or until golden brown