Nutella macarons

Preheat the oven to 140°C (275°F/gas mark 1). Mix together the icing/confectioner's sugar, ground almonds and cocoa powder. Sieve the mixture finely.

Beat the egg whites in a bowl; when they are frothy, add half the caster sugar and continue to beat. When they start to become stiff, add the remaining sugar and continue beating to make a thick meringue mixture. Using a spatula, fold in the sieved ingredients. Use large, gentle movements for at least 2 minutes, working the mixture from the edges of the bowl towards the centre. The mixture should form a ribbon when it falls from a spoon.

Cover a baking sheet with baking parchment and draw evenly spaced 3.5cm diameter circles on it. Pour the mixture into a piping bag fitted with a plain nozzle and pipe it onto the parchment in rounds the same diameter as the circles. Set aside for 20 minutes in a dry place until a crust forms on the surface.

Before putting the macarons in the oven, place the baking sheet on top of another baking sheet: that way the bottom of the macaroons will not be overcooked. Bake for 15 minutes, leaving the door of the oven slightly ajar.

Leave the macarons to cool for 5-10 minutes then remove from the baking sheet. When cold, spread half with Nutella and sandwich together with the other halves. Refrigerate for 24 hours before serving so that the macarons soften slightly.