To make the meringue, heat the sugar and 150ml water in a pan. Make sure no sugar is stuck to the sides of the pan, as this will make the syrup crystallise. Put the egg whites in a mixing bowl and whisk on a slow speed. Once the sugar has reached 116C on a sugar thermometer, increase the whisking speed to create soft peaks. When the sugar has reached 121C, pour the syrup into the egg whites slowly while still whisking at a high speed. Continue to whisk until it’s cooled to room temperature, then put in a piping bag with a 10mm plain nozzle.