Add the flour, icing sugar and xanthum gum to a bowl and mix together.
Place the butter, cheese, egg yolk and vanilla into the bowl of a food processor and then add the dry ingredients.
Pulse only until the dough starts to form a ball.. (TM speed 3, 20 seconds)
Remove the dough to a lightly floured surface and knead to form a smooth ball.
Divide the dough in half and flatten into two discs.
Cover each disc closely with plastic wrap and chill for 30 minutes.
Notes
You can store the dough in the fridge for up to two days, or freeze it until needed.
If you have time, make a batch and freeze it for when you need to whip up a quick tart or pie.
I always blind bake tart bases for 10-15 minutes (small individual), and 20 minutes (larger tarts) in a preheated oven at 170˚C (fan), then add the fruit and if required, a pastry lid, before continuing baking.
For crisper tart shells, once blind baked, reduce the heat of the oven to 70˚C (fan) and return the tart shells to the oven for an hour to dry them out.