In a large mixing bowl, combine the all-purpose flour, granulated sugar, and salt.
Add the cold, cubed butter to the flour mixture. Using a pastry cutter or your fingers, mix until the mixture resembles coarse crumbs.
Gradually add the ice water, one tablespoon at a time, mixing until the dough begins to come together. Be careful not to overwork the dough.
Form the dough into a ball, wrap it in plastic wrap, and refrigerate for at least 30 minutes.
Preheat your oven to 375°F (190°C).
On a lightly floured surface, roll out the chilled dough to your desired thickness.
Cut the dough into shapes or sizes as needed for your recipe.
Place the cut pastry onto a baking sheet lined with parchment paper.
Brush the tops of the pastries with the beaten egg to give them a golden color when baked.
Bake in the preheated oven for 20-25 minutes or until the pastries are golden brown and crispy.
Allow to cool on a wire rack before serving.