Beat the Butter till creamy. Then add the sugar and beat till it is completely dissolved and fluffy.
Now, whisk the egg in and beat well till smooth.
Now, add the flour and salt and mix till combined. Do not over mix. It should give you a big ball of dough.
Gather it nicely and wrap it in a clingwrap. Keep it in the fridge for 20-25 minutes to allow it to rest and chill.
Once you are ready, take it out and roll it out on a floured surface. Line your tart pan and prick the base and the inside edges using a fork. Freeze it once again for 15 minutes.
Pre-heat your oven.
Pop the tart pan in your oven and bake it at 200c for 5 minutes and bring down the temp to 180c and bake it for 15 minutes till the edge shrinks and turns golden. The base would also appear to be dry.
Take it out and brush the tart base with the egg white to make it waterproof. Pop it back in the oven and broil it for a minute. You can also use any jam or honey instead of the egg.
Allow it to cool on a wire rack and then use it for your pie or tart recipe.