I have Anglicized and tweaked the recipe a bit but the American version can be found here. I have made these several times now and the flexibility with the flavouring, along with the ability to keep a shape, has swiftly made them my 'go to' recipe.
You will need:
420g self raising flour (you can substitute a little of the flour with cocoa powder for a chocolate biscuit)
220g butter, cut into chunks
A few drops of vanilla essence
Cream together the sugar and butter, add the egg and vanilla and mix. Gradually add the flour and stir in until combined. You can add chocolate chips at this stage, a handful or two to add some fun to your biscuits.
Roll the biscuit dough on a floured surface to about half a cm thick, and cut into shapes. (I do this in several goes as there is a lot of dough! You could also chill some of the dough to use the next day)