Add sugar to the Thermomix bowl. Mill for 10 seconds / speed 9.
Add butter to the bowl. Cream together for 20 seconds / speed 4.
Add golden syrup and egg to the bowl. Mix for 20 seconds / speed 4.
Add flour, ginger, mixed spice and baking soda to the bowl. Mix for 10 seconds / speed 5.
Knead the dough using the knead function / 2 minutes.
Divide the dough into two and shape into two discs. Cover each disc with plastic wrap and chill in the fridge for a minimum of 2 hours. Overnight is fine too.
When ready to make the cookies, pre-heat the oven to 180C / 350F and line a baking tray with baking paper.
Generously flour your work surface and rolling pin and roll out each disc to around ¼ inch thick.
Use cookie cutters to cut out your cookie shapes and transfer to the baking tray, spacing them around an inch apart.
Bake in the oven for 8-10 minutes (see notes).
Remove from the oven and transfer the cookies to a cooling rack and allow to completely cool before icing.