Add flour, sugar, and salt in a bowl and place in refrigerator for about an hour. Refrigerating is optional, but will help in making perfect short crust pastry.
To the above bowl, add 1 stick of cold butter (cut into small cubes) and using your fingers break the butter and incorporate it into the dough. Your dough should resemble bread crumbs.
At this stage add an egg and a splash of cold milk and mix until any dry flour is not visible. The dough will be slightly tacky, but that is OK
It is very critical not to over mix the dough, else it will make the dough elastic. Quickly form a dough ball and cover it with plastic wrap and refrigerate for at least 2 hours so that the dough can relax.
Grease a 9 inch tart pan with some butter and lightly flour the surface.
Transfer the chilled dough to a well floured working surface. Dust some flour on top of the dough, and using a rolling pin roll it into a ¼ to ½ cm thick circle and whose diameter is an inch or two larger than that of the tart pan. If its diameter is larger it is fine, we can trim off the excess and use it in other recipes, but ensure that it is not too thick.
With the help of the rolling pin, transfer the dough over the greased tart pan. Tuck the dough against the edges of the pan, and run the rolling pin over the tart pan to trim off excess overhanging dough.
Using a fork, poke holes across the base of the pastry to ensure that it does not puff up during baking. Carefully transfer the tart pan to the freezer and let it freeze for an hour – or until you are ready to bake. I keep it overnight.