Put the dry ingredients into a bowl. Rub in the butter, form a well, add the liquor, eggs and egg yolks, and knead to form a soft dough. Leave to rest for 20 minutes. Cut off slices and work to make the forms of the scoccoieddus of Sant’Isidoro. Bake in a hot oven for about 20 minutes.
Prepare the icing by whisking the egg whites into stiff peaks, and then slowly add the icing sugar, stirring constantly, followed by the lemon juice and vanilla essence. Dip each biscuit into the icing and make sure they are totally covered by using a paintbrush. Add decorations and place on a baking sheet to set.