Whisk the Egg Yolks and Sugar: In a medium-sized bowl, whisk the egg yolks with sugar until the mixture is pale and creamy. This step ensures the sugar dissolves fully, creating a smooth texture. Use a hand mixer for ease if available.

Heat the Milk and Cream: In a saucepan over medium heat, combine the milk and cream. Stir gently and bring to a slight simmer, ensuring it doesn't boil. Add the vanilla extract and spices at this stage for infusion.

Temper the Eggs: Gradually add a ladle of the hot milk mixture into the egg mixture while whisking continuously. This step prevents the eggs from scrambling. Slowly incorporate all the milk.

Cook the Mixture: Return the tempered mixture to the saucepan and cook over low heat, stirring constantly. Heat until it thickens slightly but does not boil. A good test is when the mixture coats the back of a spoon.

Cool and Serve: Strain the mixture into a bowl to remove any cooked egg bits. Chill in the refrigerator for at least 2 hours. Before serving, stir in your alcohol of choice if desired, and garnish with nutmeg.