Step 1

Cream butter and sugar in an electric mixer. Add lemon rind, flour and custard powder and beat to combine. Turn onto a lightly floured bench and gently knead. Divide into 36 pieces and roll each piece into a ball. Place on a lightly floured oven tray and gently press with a fork to flatten.

Step 2

Bake for 15-17 minutes or until just starting to turn golden. Transfer to a wire rack to cool completely.

Step 3

Beat butter until very pale, add the icing sugar and lemon rind and juice, gradually adding juice until you have the desired consistency. Transfer to a piping bag.

Step 4

Fill half the biscuits with cream and sandwich each with a second biscuit.

Step 5

Dust with icing sugar to serve, if desired.