In a large bowl, combine the flour, powdered sugar, salt, and cold butter. Using your fingertips (or wearing disposable gloves), rub the butter into the dry ingredients until the mixture resembles coarse crumbs.
Then add the egg and vanilla, and continue mixing with your hands until a dough forms. Wrap the dough in plastic wrap and refrigerate for 1 hour.
Preheat the oven to 200°C (390°F), convection setting.
Once the dough is ready, butter and flour two sheets of parchment paper and roll the dough between them with a rolling pin into a round shape, 27 cm/ ~10.5 inch in diameter. If the dough sticks, add a little more flour.
Next, transfer the dough into a buttered and floured 26 cm/~10 inch round tart pan with a removable base, pressing it well to stick to the pan. Prick the entire surface of the dough with a fork.
Immediately cover the dough with beans or lentils to weigh it down, and bake in the oven for 10 minutes. Remove from oven and set aside.