Pour the whole milk into a saucepan and add the cloves, cinnamon, and nutmeg. Heat over medium heat until it just comes to a boil, stirring occasionally to combine the spices.

In a mixing bowl, combine the egg yolks and granulated sugar. Whisk them together until the mixture is light and fluffy, which usually takes about 2-3 minutes.

Gradually add a small ladle of the hot milk to the yolk mixture while whisking constantly to prevent curdling.

Slowly pour the warmed yolk mixture back into the saucepan with the remaining milk. Whisk it all together until well combined.

Return the saucepan to the stove over medium heat. Stir continuously and cook until the mixture thickens slightly and coats the back of a spoon, typically about 6-8 minutes.

Remove the saucepan from heat and strain the mixture through a fine-mesh sieve to discard the cloves and any bits of cooked egg. Let it cool for about one hour at room temperature.

Once cooled, stir in the heavy cream, vanilla extract, and optional spiced rum or bourbon until combined and smooth.

Transfer the eggnog to a pitcher or bowl and refrigerate for several hours or overnight. Serve chilled, garnished with a sprinkle of nutmeg.