First make a shortcrust pastry by putting the flour in a food processor with the chilled butter dice. Whiz to a crumb consistency then add the egg yolk, salt and
Preheat the oven to 200°C/ 400°F/ gas 6. Roll the rested pastry out and use to line a
Sweat the onions in the butter until soft. Add the flour and cook for 2 minutes. Season with salt, pepper and nutmeg, and pour over the milk. Cook over a low heat for 20 minutes, stirring at regular intervals. Off the heat, beat the yolks into this mixture.
Whisk the egg whites until stiff and fold them into the onion custard. Spoon into the pastry shell, put into the oven, lower the temperature to 190°C/ 375°F/gas 5 and bake for 15–20 minutes, until golden and risen. Serve immediately.
© 1998 Alastair Little and Richard Whittington estate. All rights reserved.