Lemony apple filling
1.Preheat oven to 180°C (160°C fan-forced).
2.To make lemony apple filling: Cut each apple quarter in half lengthways. In a large saucepan, place apples with water; bring to a boil. Reduce heat; cover. Cook for about 5 minutes, or until apples are just tender. Transfer apples to a large bowl; gently stir in sugar, cinnamon and lemon rind. Cool to room temperature.
3.To make dough: In a large bowl, add flours, custard powder, half the sugar, butter; blend or process for about 2 minutes, or until just combined. Add egg yolk and enough of the water to make ingredients just come together.
4.On a lightly floured surface, knead dough until smooth. Wrap in plastic wrap; refrigerate for 30 minutes.
5.Roll two-thirds of the dough between sheets of baking paper until large enough to line a 23cm-round pie dish. Ease dough into dish; trim edge. Cover; refrigerate for 30 minutes.
6.Roll remaining pastry between sheets of baking paper until large enough to cover pie; discard pastry scraps.
7.Spoon lemony apple filling evenly into pastry case; brush edge of pastry with some egg white. Cover filling with pastry sheet. Press edges together firmly; trim using knife. Using fingers, pinch edges to make a frill. Brush pastry with remaining egg white. Sprinkle pie with remaining sugar.
8.Bake for about 40 minutes or until pie is golden brown. Serve.
This apple pie can be made two days ahead and refrigerated, covered, but pastry will tend to soften a little under the apple.Note