Preheat oven to 190C/375F. Place butter and sugar in a bowl and beat with a hand blender till well combined, light and fluffy. Add golden syrup, flour, ginger and bicarbonate of soda. Mix to form a smooth dough. Wrap in cling wrap/plastic wrap and chill for an hour.
Roll out the dough between sheets of baking paper to 4-5mm in thickness. Using a round cookie cutter, cut out round shapes. Using a smaller round cookie cutter, lightly make an indentation in the cookie. Using a steel icing nozzle [the small, round kind], punch out four tiny holes in the middle to resemble a button and then one towards the rim [this is where the twill will pass through after the biscuits are baked].
Bake for 8-12 minutes in the preheated oven until golden brown. Remove immediately and cool on a wire rack. Don't worry if they seem floppy at this stage, just make sure they are flat and straight. The more they cool, the more they will harden and you want them nice and flat when they are hard.