Preheat your oven to 200ºC.
Line a baking tray with with baking paper and pour the caster sugar onto it. Heat it in the oven for 7 minutes or until the edges just start to go golden.
By heating up the sugar it helps to create a glossy, stable mixture. When it starts to crystalize slightly on the edges you will know that it has heated enough and it is ready.
In an electric mixer, beat the egg whites on low speed allowing small stabilising bubbles to form, and then increase the speed until the egg whites form stiff peaks.
Take the sugar out of the oven, and get the oven temperature down to 100ºC (you can leave the door open to help speed this process up)
Slowly spoon the hot sugar into the beaten egg whites with the mixture on a high speed. You need to make sure the mixture comes back up to stiff peaks after each addition of sugar.
Once all the sugar, is added continue to whisk on full speed until the mixture is glossy, smooth and stiff.
Continue to whisk for at least 5 minutes after all the sugar has been added. Test by rubbing a bit of the mixture between your fingers; if you can still feel the gritty sugar, keep whisking at full speed until it has dissolved and the mixture is smooth, stiff and glossy. To colour the meringue add a tiny drop of food colouring (use a toothpick as you only need the smallest amount) to the meringue mixture now and beat together. If you want swirls of colour, add small strips down the inside of a piping bag before putting the meringue mixture in.
Spoon the mixture into a piping bag with a nozzle or your choice and pipe tiny or larger meringues onto the baking paper.
Bake for 35-40 minutes or until the meringues come off the paper cleanly.