French macarons

Method

Sift icing sugar and ground almonds together three times through fine mesh, discarding any large almond pieces; set aside. Whisk egg whites with salt to soft peaks, then gradually add caster sugar whilst whisking to stiff, glossy peaks (approximately 3-4 minutes); fold in vanilla extract and food colouring if using. Fold the dry ingredients into the meringue in three additions, macaronning the mixture by cutting down the centre with a spatula and folding over itself repeatedly (approximately 50 strokes total) until the batter reaches a lava-like consistency that flows slightly when piped. Fill a piping bag fitted with a 10mm plain nozzle and pipe 3cm rounds onto baking trays lined with baking parchment, leaving 3cm between each macaron; tap the tray firmly on the work surface three times to remove air bubbles. Leave macarons at room temperature for 30-45 minutes until a thin skin forms on the surface. Preheat oven to 160°C (fan 140°C) and bake for 14-16 minutes until the macarons are set but still slightly moist beneath the shell; the feet should be defined and crisp. Cool completely on the tray for 5 minutes, then transfer to a wire rack and cool for 30 minutes. For the filling, cream softened butter with icing sugar and vanilla extract, then sandwich between two cooled macaron shells. Leave filled macarons at room temperature for 24 hours to mature before serving, which allows the shells to soften slightly and flavours to develop.