Heat oven to 180C/fan 160C/gas 4 and lightly oil a non-stick baking sheet. Rub together the butter and flour with your fingertips to fine breadcrumbs (or pulse in a food processor). Stir in the rest of the ingredients until you have a soft dough.
Drop 8 tbsp or 16 heaped tsp of the dough on to the baking sheet, spacing out well. Bake for 18-20 mins until golden. Transfer to a wire rack to cool and dust with plenty of icing sugar. Pack into an airtight container or gift jars.