In a small saucepan, whisk together all of the ingredients until smooth.
Place on the stove top over the lowest heat.
Cook, whisking continuously, until the eggs have just cooked, the eggnog has thickened and it coats the back of a spoon.
Enjoy warm or cool, then place into the fridge to chill.
Either way, you could enjoy your eggnog topped with plenty of whipped cream.