Cream Sugar's and Butter together until light and fluffy
Wisk in vanilla extract and egg
Stir in flour and cocoa
Mix in all the chocolate
Empty on to a flour dusted surface and flatten
Use a 2 1/4 in or 58mm cutter (can go bigger, but will make less cookies) and cut out your cookies and place on to a none stick tray (If tray is not stick pre grease your tray)
Bake in a fan forced oven on 160c (320F) for 10mins.