Step 1

Preheat oven to 200°C. Line 2 baking trays with baking paper.

Step 2

Place butter, sugar and lemon zest in the bowl of an electric mixer and beat until light and creamy. Add egg yolks, 1 at a time, beating well after each addition.

Step 3

Sift flour and a pinch of salt into a bowl, then stir in polenta. Add dry ingredients to egg mixture and beat until combined.

Step 4

Knead lightly for 1-2 minutes and form dough into a ball. Enclose in plastic wrap and chill for 30 minutes to firm up.

Step 5

Roll out the dough on a lightly floured surface until 5mm thick and cut out circles using a 6cm-pastry cutter. Use a palette knife to gently lift biscuits and place on trays. Bake for 10-12 minutes until light golden. Cool on wire racks.

Step 6

Biscuits can be stored in an airtight container for up to 1 week.