Quickly work 450g of all-purpose flour, 160g of sugar, 200g of cold diced butter, 2 medium eggs, and a little grated lemon zest into a smooth dough. Wrap and chill for 30 minutes.
Heat 750ml of whole milk with a strip of lemon peel. In a saucepan, whisk 3 eggs, 1 egg yolk, 225g of sugar, 35g of cornstarch, and 30g of all-purpose flour.
Remove the peel and gradually whisk the hot milk into the egg mixture. Cook gently, stirring, for 10-15 minutes, until thick, then cover and cool.
Preheat the oven to 325°F / 160°C. Roll out most of the pastry to line a 10in / 25cm round pan, fill with the cooled custard, and cover with the remaining pastry rolled into a disc. Seal the edges and sprinkle with 25g of pine nuts.
Bake on a low shelf for 50 minutes, then on the middle shelf at 350°F / 180°C for 10 minutes. Dust with icing sugar once cooled.
