Place the icing sugar into a clean and dry Thermomix bowl and soft for 8 seconds, Speed 8. Scrape down the sides of the bowl.
Add the chopped butter and plain flour and mix for 10 seconds, Speed 6.
Knead (using the Kneading function) for 1 minute and 30 seconds.
Form the dough into a ball, wrap in plastic wrap and chill in the fridge for 30 minutes.
Preheat the oven to 160 degrees celsius (fan forced). Line two flat baking trays with baking paper and set aside.
On a lightly floured board or bench, roll the dough out to 1cm thick. Cut the dough out using a circle cutter.
Place the circles onto the prepared trays and bake for 10-12 minutes or until just ever so slightly golden around the edges.
Allow to cool on the trays for 10 minutes before transferring to a wire rack to cool completely.
Notes
RECIPE NOTES & TIPS
there is no rising agent used in shortbread - this is because we want it to be flat and buttery rather than fluffy
either salted or unsalted butter is fine to use
the kneading function may also be called the dough function - depending on the model of your Thermomix
it's important to chill the dough so that the butter solidifies and your biscuits don't spread when baked
if you have chilled the dough for considerably longer than 30 minutes, you may need to leave it at room temp for 10 minutes before rolling it out (so that it doesn't crack).
don't overcook the shortbread - it should hardly change in colour at all. Please note, that the shortbread will be soft when you remove it from the oven and it will firm up as it cools.
Store shortbread in an airtight container at room temperature for 1-2 weeks.
Alternatively, you can freeze the unbaked dough or the baked biscuits for up to 1 month.