In a medium saucepan over a low heat, bring the milk to a gentle simmer.
In a medium bowl, whisk the eggs, egg whites, honey, vanilla extract, and ground nutmeg together.
Temper the egg mixture - which is really the only tricky part to the whole recipe. However, if you try to rush this step, you might just suddenly discover that you've made scrambled eggs! Delicious, no doubt, but not really the goal here!!
Pour about ½ a cup of the simmering milk into the egg and honey mixture and continue to whisk.
Then slowly keep adding the milk to the egg and honey mixture until approximately half of the milk has been added to the bowl.
At this point, we're hoping that you have a lovely consistency and not something chunky that you might serve atop hot, buttery toast on Sunday morning!
Continue whisking.
Now gently pour the contents of the bowl (the egg, milk, and honey mixture) into the saucepan.
Keep whisking!
Turn the heat up a little bit while continuing to whisk.
You’re wanting to thicken the eggnog mixture until it can coat the back of a spoon. That will take around 6 - 7 minutes.
While the eggnog is thickening, you will need to prepare an ice bath (only for the eggnog - not for you!).
To make an ice bath, fill a large bowl with ice cubes. Rest a slightly smaller bowl on top of the ice - making sure that it's relatively stable.
When the eggnog has thickened, carefully pour the mixture into the top bowl, ensuring the top bowl doesn't over-balance. The ice bath will cool rapidly cool the eggnog and help it to thicken some more.
If you have gone for the brandy, rum, or whiskey option, stir those 4 tablespoonfuls in just after the eggnog has cooled. (If you add it while the eggnog is hot, the alcohol content could be diminished.)
Once the eggnog has chilled, pour it into glasses and dust the top with a light sprinkling of the ground nutmeg to garnish.
Notes
If you have chosen the alcohol stir-in option, please do be aware of the alcohol content - for you and your guests - when deciding whether or not to drive.