1 For the pastry, sift the flour and salt into a large bowl, then rub in the TREX until the mixture looks like breadcrumbs. Stir in the sugar and egg yolks, then draw the mixture together to form a dough. Knead lightly for a few seconds, then wrap and chill for 10-15 minutes.
2 Put the ball of dough into the middle of a 20cm (8 in) flan dish or pie plate and press it out gradually using the back of a large spoon, until you have worked the dough evenly over the base and up the sides. Chill for 15 minutes.
3 Preheat the oven to 220°C/fan oven 200°C/Gas Mark 7.
4 Prick the pastry base with a fork. Line with foil, and bake for 10 minutes. Remove the foil, reduce the temperature to 180°C/fan oven 160°C/Gas Mark 4 and bake for 5 more minutes.
5 For the traditional filling, blend the cornflour and water until smooth. Heat in a saucepan with the butter and half the sugar, stirring until thickened. Remove from the heat and add the lemon rind and juice. Lightly beat the egg yolks, stir into the lemon mixture and pour into the flan case. Bake for 15-20 minutes, until set.
6 For the cream filling, mix the condensed milk with the lemon juice and rind. Lightly beat the egg yolks, stir into the lemon mixture and pour into the flan case. Bake for 15-20 minutes, until set.
7 Whip the egg whites in a grease-free bowl, gradually whisking in the remaining sugar until stiff and very glossy. Pile on top of the lemon pie, then bake in the oven for 8-10 minutes, until golden brown.
Recipe courtesy of Trex