Mexican Eggnog

Put milk and sugar into a medium pan on the stove and heat at medium-high temperature until it boils.  Reduce heat and simmer for 10 minutes, stirring constantly.  Remove from heat and cool to room temperature.  Separate eggs and discard whites.  Beat yolks with a fork until they are thick and frothy.  Add yolks slowly to the milk and sugar mixture.  Beat mixture gently until the yolks are integrated into the milk and sugar.  Add remaining ingredients.  Put mixture back on the stove and cook on medium heat, stirring constantly, until the mixture thickens enough to coat a spoon.  Store in a covered glass container in the refrigerator for at least 48 hours before serving.