Make the sugar by placing sugar and zest into Thermomix bowl and milling for 8 sec/speed 10. Use 120g in shortbread and reserve the rest.
Preheat oven to fan forced 180ºC and line a baking tray with paper.
Add butter to sugar in Thermomix bowl and chop for 4 sec/speed 6.
Add remaining shortbread ingredients and blend for 10 sec/speed 6. Tip dough out onto floured Silpat mat. Divide into two portions. Roll each into a long sausage shape with a 3-4 cm diameter.
Roll in remaining Orange sugar. Cut into small rounds, place onto tray and flatten with your thumb.
Bake for 12-15 minutes until golden and fragrant. Cool before keeping in an airtight container in fridge for optimum crunch factor!
These are a darling gift when wrapped in lots of cellophane and truckloads of curling ribbon…and as for the sugar, it also is a pretty nice gift for the foodies in your life!