Mix the butter and sugar in a large bowl with a wooden spoon.
Add the egg yolk and vanilla extract and briefly beat to combine.
Sift over the flour and stir until the mixture is well combined – you might need to get your hands in at the end to give everything a really good mix and press the dough together. Chill for 20-30 mins.
Pre-heat the oven to 180C/160C fan/gas 4. Chill the dough for 20 - 30minutes, roll out and cut out shapes. Bake on a non-stick baking tray for 10-12 minutes until pale golden. Carefully transfer to a wire rack to cool and crisp up.
