Preheat your oven to 160 degrees Celsius (320 degrees Fahrenheit) and line a baking sheet with parchment paper.

In a mixing bowl, combine the icing sugar and ground almonds. Sift to remove any lumps.

In a separate bowl, whisk the egg whites with a pinch of salt until foamy, then gradually add the caster sugar while whisking until stiff peaks form.

Gently fold the almond mixture into the egg whites. If desired, add red food coloring.

Fill a piping bag with the macaron batter and pipe small circles onto the prepared baking sheet.

Let the piped circles rest for 30 to 60 minutes.

Bake the macarons for 15-18 minutes until they have a firm outer shell.

Let them cool completely on the baking sheet.

Make the buttercream by beating the softened butter, then gradually adding icing sugar and raspberry puree until smooth.

Pair up the cooled macaron shells, spread a small amount of raspberry buttercream on one shell, and sandwich it with another.

Chill the assembled macarons in the fridge for a few hours before serving.