Mix together the egg whites, caster sugar, golden syrup, cream of tartar, pinch of salt and 1 tablespoon of cold water in a large heatproof bowl.
Place bowl over top of a pot of simmering water, making sure the bowl doesn't touch the water. Beat mixture with a handheld mixer for about 5 minutes or until sugar has fully dissolved and stiff peaks start to form.
Remove bowl from the heat, add vanilla extract and beat for a further minute until icing is light a fluffy. Pipe, blob, cover or fill with this marshmallow meringue icing straight away. For that added toasted effect, feel free to blast with a blowtorch too - tastes amazing!