To make the crust, mix the flour, sugar and salt into a large bowl or into the food processor.
Add the cold butter and pulse or mix to obtain a crumble.
Add the ice cold water one tablespoon at a time, and process or knead to obtain a dough.
Cover in plastic foil and refrigerate for at least 2 hours.
Preheat the oven to 200 C/390F.
Line a baking sheet with parchment paper.
Roll the dough onto a floured surface to obtain an approximate 8'x11' rectangle. Transfer onto the lined sheet.
Arrange the apple slices onto the dough to create a pattern, leaving 2' of dough free for folding.
Drizzle the apples with lemon juice and sprinkle the cinnamon on top.
Fold the dough border to create the crust. Brush with beaten egg yolk, sprinkle with sugar and bake for 30 minutes, until golden and flaky.
Remove from the oven and let cool for 10 minutes before serving.