Step 1

Preheat oven to 180°C (160°C fan-forced). Grease two oven trays; line with baking paper.

Step 2

Beat butter, rind and sifted icing sugar in a small bowl with an electric mixer until just combined; stir in polenta and sifted flour. Turn dough onto a lightly floured surface; knead 1 minute or until smooth.

Step 3

With a lightly floured rolling pin, roll dough until 5mm (¼-inch) thick. Using a small sharp knife, trim edges to make a neat rectangle. Cut dough into 4cm x 6cm rectangles (1½-inches x 2½-inches). Place rectangles 2cm (¾-inch) apart on trays. Gather dough scraps; repeat rolling and cutting until all dough is used.

Step 4

Prick each biscuit three times with a fork. Bake 15 minutes or until light golden. Remove from oven, sprinkle hot biscuits with caster sugar; stand for 5 minutes before transferring to wire racks to cool.