This recipe makes about 150 biscuits

Ingredients

200 g        Butter (at room temperature)
200 g        (+2 heaped tsp) flour
200 g        Icing sugar
5               Egg whites (at room temperature)
1tsp          Vanilla extract
1               Lemon zest
1               Orange zest

Method

Beat butter on its own in a mixer with a whisk at high speed for about 3 minutes.  Lower speed to medium and add icing sugar, a spoonful at a time, and mix well, scraping down ingredients from the side of the bowl.   Sift flour in a separate bowl and with the speed of the mixer at medium to low, add flour into the butter-sugar mixture, adding intermittently one egg white, then flour, then one egg white, then flour, and at the end add the vanilla, and the lemon and orange rind.

Line two large trays, or four if you have them, with grease-proof paper, and then pipe through a small nozzle, thin strips of about 6cm long.  Keep some space between biscuits as they will spread.

Bake in a preheated oven of 204ºC (400ºF) for 12 min.  Take out of the oven, and when cool, remove from the grease-proof paper and store in a tin.

If you like to cover part of the biscuit with chocolate, melt 100g of dark chocolate, plus 1 tbsp of butter in a pan over simmering water (bain-marie).  Once the chocolate is melted and well-stirred, place it into a narrow coffee cup.  This is so that the melted chocolate does not spread within a wider container, in which case it would be difficult and not practical to dip the biscuits in.  Dip each biscuit, so that approximately ⅓ of it is covered in chocolate, shake it well and place on a rack, until completely cooled down.