Cut the butter into cubes and leave at room temperature to soften.
Fit the K beater to the machine.
Add Ingredients 1 (butter, flour, salt, icing sugar) into the Mixer bowl.
Attach the Mixer bowl to the machine and fit the splash guard.
Mix on speed 2 for 2 minutes.
Add Ingredients 2 (egg) into the Mixer bowl.
Mix on speed 2 for 1 minute .
Transfer the pastry to a worksurface.
Knead until the mixture comes together.
Wrap in plastic wrap.
Chill in the fridge for 30 minutes.
Use.