Using a mixer, beat egg yolks in a large bowl until they are pale in color. Slowly add the sugar while continue to beat.
In a medium sized sauce pan or double boiler, combine milk, cinnamon and cloves, and heat until not - but not boiling.
While continually mixing, very slowly pour half of the hot milk mixture into the egg yolks. Once blended, add the remaining hot milk while mixing constantly, then pour everything back into the saucepan.
Heat mixture over medium heat, stirring constantly with a wooden spoon, do not allow to boil. Once mixture begins to thicken slightly, and coats the back of the spoon it is ready (or temperature reaches 160°F).
Set aside to to cool for an hour.
Stir in the vanilla and alcohol, and chill until ready to serve.
For a dairy free version, use almond milk or canned coconut milk. They will give you the best consistency for egg nog.