What you need:

3 egg whites at room temperature
256g icing sugar
256g light corn syrup (easily found on Amazon or online American food stores)
1/2 tea spoon of salt 
Natural vanilla essence 

Step one: Weigh the icing sugar and corn syrup in preperation and leave them to one side. Seperate three egg whites into a bowl.

Step two: Place the egg whites, corn syrup and salt into your mixer and leave on high speed for 5 minutes. This will be done when it turns white in colour.

Step three: Now add the icing sugar little by little as you continue to mix your ingredients on a low speed. Once the icing sugar has been intregrated it is time to pour in your chosen flavouring (this can be adjusted acording to taste). Once your 'Fluff' has gained volume it is done.

Now you are ready to adorn your cakes with your homemade marshmallow cream or 'Fluff'!