With an electric hand mixer, whisk the egg whites until the mixture is foamy. Add a pinch of salt, then add the caster sugar half at a time. Whisk the mixture until soft peaks are formed.
Once the sugar is incorporated, add the food colouring and whisk the mixture to stiff peaks.
Carefully sieve in the almond and icing sugar mix, then fold this through. Using your spatula press some of the mixture against the side of your bowl to reduce the amount of air bubbles in your mixture. You are looking for a dropping consistency.
Once combined, put the mixture into a piping bag fitted with a 1cm nozzle.
Pipe 3.5cm rounds onto the a baking sheet lined with non-stick baking paper (leave a few cm between each one. For perfectly round macarons you can use a template underneath the baking paper).
Slam the macaron tray down on the counter a few times - to help shape them and get rid of any bubbles. Let them sit for at least 45 mins until a skin forms on the surface.
Bake the macarons for 10 - 12 minutes, depending on their size.
Remove the trays from the oven and allow to cool. Ensure the macarons are completely cooled before you remove them from the paper.
Construct your macarons by piping a ring of buttercream then fill with jam. Decorate to your liking, and serve.
