Step by step

1. In the stand mixer bowl, combine the butter and icing sugar.

2. Set the whisk accessory and whip at speed 4 for at least 5 minutes until fluffy.

3. Strain the egg whites, gently adding to the dough, then reduce the speed and combine the flour and starch, than the grated lemon skin and a pinch of salt.

4. Transfer the dough in a piping bag with a grooved tip.

5. Shape the biscuits on a baking tray, lined with parchment paper.

6. Bake at 180°C for 15-18 minutes.

7. When ready, let biscuits cool. Store in a metal tin for several days, if necessary.