Put a little water in a medium saucepan and bring to a boil over high heat then lower heat to let water simmer.
Use a bowl big enough to sit on top of the saucepan. Put egg yolks and sugar in the bowl, add brandy or rum or whisky and using whisk, whip until sugar is dissolve, and continue whipping over simmering pot of water until mixture is double in volume.
Take off of the heat and let cool. (if not using immediately, you can keep it in a fridge, covered. Use within 2-3 days