In a small saucepan, combine sugar and the water; stir with a wooden spoon over high heat, without boiling, until sugar dissolves. Boil, uncovered, without stirring, about 3 to 5 minutes or until syrup is slightly thick. If a candy thermometer is available, the syrup will be ready when it reaches 114°C.

Otherwise, when the syrup is thick, remove the pan from the heat, allow the bubbles to subside then test the syrup by dropping 1 tsp into a cup of cold water. The syrup should form a ball of soft sticky toffee when rolled gently between your fingertips.

The syrup should not change colour; if it does, it has been cooked for too long and you will have to discard it and start again.

Meanwhile, in a small bowl, beat egg whites with electric mixer until stiff; keep beating (or whites will deflate) until syrup reaches the correct temperature.

When syrup is ready, allow bubbles to subside then pour a very thin stream onto the egg whites with mixer operating on medium speed. If syrup is added too quickly to the egg whites, frosting will not thicken. Continue beating and adding syrup until all syrup is used. Continue to beat until frosting stands in stiff peaks (frosting should be barely warm by this stage).

Tint frosting, if desired, by beating food colouring through while mixing, or by stirring through with spatula at the end. Frosting can also be flavoured with a little of any essence of your choice.

For best results, frosting should be applied to a cake on the day it is to be served, while the frosting is still soft and has a marshmallow consistency. While you can frost the cake the day before, the frosting will become crisp and lose its glossy appearance, much like a meringue.