Separate the eggs and place in a clean bowl with the sugar.
Whisk together well and then whisk in the Baileys.
Heat the water to a simmer in a bain-marie and whisk the mixture for about 5 minutes, trying to incorporate as much air as possible.
Allow to cool or place the bowl over a bowl of iced water.
In a separate bowl whisk two of the egg whites to stiff peaks and fold into the mixture.
Decorate with chocolate shavings and mint if liked.
Notes
Tips:
Put the eggs in the fridge before using as this helps when you are separating the eggs from the yolks. I use two small bowl for separating and add the yolks one at a time, in case there is a bad egg.
Don't tip the sugar directly onto the egg yolks as they can start reacting and make the egg tough.