Put the flour, cold, cubed butter and 50g (¼ cup) of the sugar in a bowl.
Rub together until you have an even crumb.
Add the dried lavender and mix through.
Add 1 tbsp of cold water and cut through with a cutlery knife. Give a little bit of the mixture a squeeze. If it comes together, it’s ready. If it’s dry and sandy, cut in up to another 1 tbsp water.
Gather and knead the mixture just enough to bring it together as a smooth dough. Be careful not to overwork it.
Roll out the dough to about 1 cm (½ inch) thick and then cut out rounds using your 4-5cm (2 inch) cutter.
Transfer the rounds onto trays lined with baking paper. Put the trays in the fridge for at least 15 minutes until very firm.
While the biscuits chill, preheat the oven to 170C (150C fan / 340F).
Bake for 20-25 minutes until they've taken on just a very slight golden colour.
As soon as they’re out of the oven, sprinkle with the remaining sugar and allow to cool for 5 minutes. Transfer to a wire rack to cool completely.