Preheat the oven to 150 °C.
Sieve the icing sugar, discard the impurities and hard lumps.
In a clean and grease free mixing bowl whisk the egg white until it starts to aerate and lightly foam, add the caster sugar and continue whipping until a soft peak meringue forms.
Add food colouring of your choice (optional) and the sifted almonds to the meringue and mix lightly until just incorporated. Do not over mix.
Spoon the mixture into a piping bag, I prefer using disposable piping bags however any type will be appropriate.
Cut a 1cm gap at the point of the piping bag.
Line two large baking trays with parchment paper, spread a dash of the mixture underneath the paper to stick it to the tray.
Pipe 2cm macaron droplets evenly sized and  spread with a 3cm gap between each.
Leave the macarons to form a skin, about 10 - 20 minutes.
Sprinkle on your chosen garnish, optional.
Bake the macarons for 12 - 15 minutes in the preheated oven.
Let them cool on the tray for 5 minutes before transferring  to a cooling rack to cool completely.
Dust each half macaron with edible glitter, optional.
Loosen the macarons carefully from the baking paper, pair them up in lines with  one half turned over so that the flat side points up.
Pipe the filling of your choice on the flat side of one half and then sandwich the two halves together.
Keep them in a airtight container for up to 5 days.

Macaroon Flavourings and Fillings on request