Separate the eggs, putting the whites aside (keep for meringue).
In a medium bowl, whisk the egg yokes with the sugar until it’s light.
Warm cream, milk, and nutmeg over medium heat.
Once the mixture starts simmering gently, begin adding spoonfuls of hot milk to the egg yokes.
Whisk vigorously with each spoonful (no more than ½ cup at a time).
Once you’ve used all the milk mixture, return everything to the pan.
Continue whisking until the beverage reaches 160 degrees F.
Remove from the heat.
Add extract (and alcohol, if desired).
Put into a covered pitcher. Note that it gets thicker as it cools.
Serve with whipped cream and nutmeg on top.
This can remain in your refrigerator for up to a week.
Serve hot or cold.