Preheat the oven to 150°C.

Place icing sugar and ground almonds in a food processor and blend for 30 seconds (the icing sugar and almond meal should be well blended in order to ensure a finer texture and an even distribution when this dry mixture is later folded into the egg whites).

Remove and sieve the mixture to remove any lumps or coarse almond pieces.

Whisk egg whites until just foamy and thick – take care not to over whisk the egg whites, as the mixture will become too thick to hold the almond mixture.

Slowly add caster sugar and a small drop of food colouring and whisk until soft peaks form.

In four separate batches, gently fold the sieved almond mixture into the egg white mixture using a large metal spoon – again, do not over work.

Place in a piping bag fitted with a round nozzle and pipe 40 evenly sized rounds, 3 cm apart, onto a lined baking tray.

Tilt the baking tray slightly to allow the macaroons to spread evenly. Bake for 15 to 20 minutes. Leave to cool completely before removing the macaroons from the baking tray.

Sandwich the macaroons together with a coloured butter filling – for a neat finish, pipe the filling onto one round and gently stick another on top.

Note: You can also fill them with a ganache

To make the butter filling: Whisk together the butter and  caster sugar until light and fluffy. Mix in a few drops of the food colouring of your choice if you wish.

Cook’s note: Do not open the oven during the first 10 minutes of baking as this will cause the egg whites to deflate.