Ricciarelli biscuits

Whisk the egg whites to stiff peaks in a clean bowl, then whisk in the almond extract and lemon zest.

In a separate bowl, sift together the icing sugar, ground almonds and a pinch of salt. Gently fold this into the whisked egg whites until it all comes together into a dough. Cover and chill for at least 4 hrs, or ideally overnight.

Heat the oven to 190C/170C fan/ gas 5. Turn the dough out onto a work surface generously dusted with icing sugar. Roll into a long, fat sausage (about 40cm long) and cut 2cm-thick slices down the length (you should get about 20). Shape each slice into an oval and pat down the tops a little – the biscuits should be about 4-5cm wide and 5-6cm long. Arrange on a baking tray lined with baking parchment and dust with more icing sugar.