Preheat oven to 170ºC/325ºF/Gas Mark 5. Cover a large baking tray with grease proof paper.
Mix the icing sugar, almonds and your 40g of egg whites in a large bowl until it forms a paste.
Heat the water and caster sugar in a small pan until the sugar melts. Once it has melted turn up the heat and boil until the mix has turned into a syrup.
Whisk your remaining 50g of egg white until medium-stiff peaks are formed. Add the syrup and whisk. The mix should become shiny and stiff.
Add a few drops of food colouring if you wish to colour the macaroons. Then add this meringue mixture to the almond paste. Continue to stir gently until the mix is once again shiny and stiff.
Spoon your mix into a piping bag and pipe about 4cm flat circles onto the lined tray. Make sure they are about 2cm apart from one another. For a smooth finish make sure the mix is nice and loose. To get rid of the little ‘tip’ that will form on top after piping, hit the tray off a flat surface a few times to flatten the macaroons.
Add the coconut on top if you wish or you can leave it out. Leave the macaroons stand for about half an hour until a skin is formed. Then pop into the oven for 12-15 minutes. Leave the oven door slightly ajar and take out the macaroons when they are firm.
Take the grease proof paper off the tray and leave the macaroons cool.
When they have cooled, stick two macaroons together with the whipped cream.