Rompope is a drink made with eggs, milk, and vanilla.It is often called “Mexican eggnog.” It can be eaten with a spoon like ice cream, although men mix it with rum or brandy. It is said to have originated at the Convent of Santa Clara in Puebla in Mexico.

Gourmet Sleuth offers this recipe (but there seem to be many variations):

I N G R E D I E N T S
4 cups milk
1 cup sugar
3 inches canela (cinnamon bark)
1/4 teaspoon baking soda
12 egg yolks
1/2 cup brandy
I N S T R U C T I O N S
In a medium sized saucepan over medium heat, mix together the milk, sugar, cinnamon bark and baking soda. When it begins to boil, lower the heat stand simmer for about 20 minutes. Set aside to cool, and strain to remove the cinnamon bark.

Place the egg yolks in a mixing bowl and whisk or beat with an electric mixer about 5 minutes. , until thick and lemon yellow. While still beating, slowly, pour the cool milk mixture into the yolks. Return to the saucepan and cook over low heat., stirring constantly, until the mixture thickens and lightly coast the back of a wooden spoon.

Remove from the heat and stop the cooking by pouring the rompope into a bowl (preferably metal) that is resting on ice in a larger bowl. Stir until cool. Gradually stir in the brandy and it’s ready to serve, or it can be tightly covered in the refrigerator.

The Big Apple has more rompope information and recipes.