To Make the Dough

1. Preheat the oven to 170°C fan (350°F). Line a baking tray with parchment paper.
2. Beat the softened butter at medium-low speed until light and fluffy.
3. Sift in the icing sugar, then roughly mix it in by hand. Switch to a handheld mixer and beat until well combined.
4. Add the lemon zest and lemon juice. Mix gently with a spatula — the mixture may look slightly separated, but that’s normal.
5. Sift the cake flour and cornstarch into the bowl. Roughly mix with a spatula, then beat with the mixer at medium speed until a dough forms.

To Roll and Chill the Dough

1. Shape the dough into a ball using a spatula.
2. Divide the dough in half. Sandwich each portion between two sheets of parchment paper and roll to 6 mm thickness.
3. Place the rolled dough on a baking sheet or pan and chill for at least 30 minutes, or until firm to the touch. This helps give the cookies sharp edges when cut.
   

To Cut and Bake the Shortbread Cookies

1. Use your desired cookie cutter to cut out shapes and arrange them on the lined baking tray, spacing them about 1 inch apart. They won’t spread much
2. Gather and re-roll any scraps between parchment paper, chilling again if the dough becomes too soft.
3. Bake for 18–20 minutes, or until the edges are just turning golden.
4. Let the cookies rest on the tray for 10 minutes before transferring to a wire rack to cool completely.
   

To Make the Icing

1. In a small bowl, mix the icing sugar and lemon juice until smooth and drizzling consistency. Adjust with a drop more juice if too thick, or more icing sugar if too thin.
2. Transfer to a piping bag, secure the top, and snip a small hole at the tip.

To Decorate the Shortbread Cookies (Optional)

1. Place a sheet of parchment paper on your work surface to catch any drips.
2. Drizzle the icing over the cooled cookies in a zigzag motion.
3. Allow 10–15 minutes for the icing to set before serving.