Melt the chocolate over the boiling water or in the microwave. Let cool completely.
In a bowl, whip the yolks with sugar at high speed until fluffy.
Add condensed milk, melted chocolate and alcohol. Whip until the sugar is completely dissolved. Give it a taste and add more alcohol if need.
If you want this eggnog to be runnier, add pre-boiled milk. However, if you want the eggnog to be thick, leave it in a fridge for a few hours. If you added the exact same measurements, you get a thick chocolate eggnog.
