Weigh out all the ingredients, line two baking sheets with greaseproof paper and have a piping bag with round nozzle ready.
Place the icing sugar and almonds into a food processor and blend for about 30 seconds until thoroughly mixed and transformed to a fine powder.
Tip the egg whites into a spotlessly clean, dry mixing bowl; add the salt and whisk until they will just hold a stiff peak.
Continue to whisk and add the caster sugar a teaspoonful at a time, mixing well between each addition. The mixture will become thick and glossy.
Add the raspberry & rose cordial and pink food colour and mix until the colour is evenly blended.
Fold in the icing sugar and ground almonds using a metal spoon, until the mixture is thoroughly combined and smooth.
Fill the piping bag and pipe evenly sized rounds about 5cm in diameter onto the lined baking sheets. Tap the bottom of the baking sheet sharply onto the work surface, just once, to get rid of any large air bubbles.
Leave the macarons for at least 30 minutes, up to 1 hour or so they set and form a dry shell. They should not be sticky or tacky when tested with your fingertip.
Preheat the oven to 170°C, 150°C fan, Gas 3. Bake the macarons one sheet at a time for 10-15 minutes until the tops are crisp and the bottoms dry. Leave to cool on the baking sheet.
To make the butter cream beat the butter and icing sugar together until smooth and fluffy, then add the Raspberry & Rose cordial and mix until evenly distributed.
When cool, spread some buttercream onto half of the macaron shells, then sandwich with the other half and leave for about 30 minutes before serving.
To ensure that your macarons are the same size, draw 5cm diameter circles onto the baking parchment, turn it over and then pipe the mixture onto each circle.
For a more aromatic rose flavour, add rose water to the macaron mixture