Combine the milk, sugar, vanilla extract, cinnamon stick, and ground almonds (if using) in a large saucepan.

Heat the mixture over medium heat, bringing it to a boil.

Reduce the heat to low and simmer, stirring constantly, for 15 minutes.

Remove the saucepan from the heat and allow the mixture to cool to room temperature.

In a separate bowl, beat the egg yolks until they are thick and pale yellow.

Remove the cinnamon stick from the cooled milk mixture.

Gradually whisk the beaten egg yolks into the milk mixture.

Return the saucepan to low heat and cook, stirring constantly, until the mixture thickens enough to coat the back of a spoon.

Remove from the heat and let the mixture cool completely.

Stir in the rum or brandy.

Transfer the Rompope to a container with a tight-fitting lid.

Refrigerate for 1 to 2 days before serving to allow the flavors to meld.