Preheat the oven to 160'C.
Make the macaroon shells: place the ground almonds and the icing sugar in a food processor and mix to give a fine, lump-free powder.
Place the water and the caster sugar in a saucepan and heat to 118'C, stirring continuously. Whilst this mixture is heating, whisk 75g of egg whites. Once the sugar has reached 118'C, add it to the egg whites and whisk until the mixture cools down. Add the food colouring and mix gently.
Add the remaining egg whites to the icing sugar and almond mixture. Add a spoonful of the meringue mixture, mix together and then fold in the rest of the meringue. Once the mixture reaches the ribbon stage, place it in a piping bag and then pipe the macaroons on to a lined baking sheet. Gently tap the baking tray down on to the work surface. Transfer to the oven and cook for 10 minutes, turning the baking tray around after 5 minutes.
«It's a good idea, after piping, to leave the macaroons to rest for 10 minutes before cooking.»