Wash the leeks carefully and slice them finely. Beat the eggs with the REGILAIT semi-skimmed milk powder and set aside.
In a saucepan, bring a large glass of water, a knob of butter and a pinch of salt to the boil and add the leeks.
Cover and cook for three minutes.
Remove the pan from the heat and pour the contents into the egg and milk mixture. Season with pepper.

Line a tart tin with the shortcrust pastry. Pour the mixture into the pastry and divide the grated cheese over the top.

Cook in a hot oven (7-8/425-450ºF/220-230ºC) for 30 minutes. Serve warm.