Process flour, sugar, and salt in a food processor for a few seconds until combined. If you don’t have a food processor, you can do this by using a pastry cutter.
Add cold butter and pulse until mixture becomes crumbly and resembles coarse meal, about 15 pulses
Add egg and keep pulsing until the dough is no longer dry and starts to clump together for about 10-15 seconds.
Do not process to the point that a large ball of dough is formed; rather the dough should be quite crumbly with large clumps.
Turn dough to a lightly floured surface and form into a ball. It should come together easily without being sticky. Flatten the ball slightly with your hands to form a thick disc. Wrap with plastic wrap and refrigerate for at least 1 hour.
Remove the dough from the fridge and allow it to sit for a few minutes before using.
On a lightly floured surface, roll the dough out into an 11-inch circle, then place gently into a 9-inch tart pan (preferably with a removable bottom); you can do this by flouring a rolling pan and rolling the dough loosely around it, then unrolling it into the pan. Brush away any excess flour on the surface. With a sharp knife, trim the edges of the pastry to fit the tart pan. Cover the pan with plastic wrap and place in the freezer for about 30 minutes. This will help prevent the dough from shrinking.
Preheat oven to 375F and place rack in the center.
Press parchment paper or aluminum foil tightly against the crust, covering the edges to prevent them from burning. Fill with pie weights/dried beans/uncooked rice, making sure they’re fully distributed over the entire surface.
Bake crust for 25-30 minutes, until foil no longer sticks to the dough. Transfer crust to a wire rack and remove weights and foil.