Cream together the butter and sugar until light and creamy.
Add the egg, vanilla and salt.
Gradually add the flour and mix together. Bring together to a dough. Wrap in a cling film and refrigerate for 2 hours.
Preheat the oven to 180 degrees.
Cut the dough to 4 batches and on a waxing paper, roll out the dough into a thin layer.
Cover with a waxed paper and place in the freezer. Proceed with the rest of the dough. I usually leave them for just 5 minutes, this technique helps a lot with a cutting procedure.
Bake the cookies for 15 minutes maximum or until slightly golden.