Combine the flour, butter, sugar, and salt in a bowl and work with your fingers into a sandy consistency, with pebble sized pieces throughout. Add the egg wash and incorporate with a fork.
Combine it all together and flatten into a thick disc. Wrap in plastic and freeze for 30 minutes or refrigerate for 60 minutes.
Remove the dough from the freezer and bang on it with a rolling pin. On a well floured cutting board or surface, roll it out until about 1/8 inch thick. Flip the cutting board over onto a tart pan with a removable bottom. Press into the contours of the pan and trim for neat edges. Freeze the dough in the tart pan for 30 minutes.
Preheat the oven to 375 degrees F. Cook the shell for 20 minutes then remove from the oven and let cool for 5 minutes.
Place the tart pan onto a baking sheet. Pour the filling into the shell. Place the baking sheet in the oven and bake at 325 degrees F for 20 minutes, then raise the temperature to 350 degrees F and cook for 20 minutes more, until set, a bit bubbly, and only slightly jiggly.
Let cool to room temperature before serving.