Preheat the oven to 180˚C. Grease 2 x 12-hole mini muffin tins.
Make the pastry by creaming the butter and sugar until light and fluffy. Add the egg yolk and beat well. Stir in the flour. Gather the dough into a ball, wrap in plastic wrap and refrigerate for 20 minutes.
Roll pastry out on a lightly floured surface to a thickness of 2-3mm. Using a 7cm round biscuit cutter cut circles from the pastry and place in the prepared tins.
Prick bases with a fork and freeze for 5 minutes to reduce shrinkage when baking.
Bake for 10 minutes until golden. Remove pastry cases from the tin and place on a wire rack to cool.
Just before serving fill with lemon curd and dust with icing sugar.