Pour the milk into a medium pot and set on medium heat to warm the milk. Do not boil.

Separate the egg yolks from the egg whites and reserve both.

In a medium bowl, beat egg yolks, sugar, flour and salt until well combined.

Using spoonfuls at a time, add warm milk to the egg yolk mixture, until about 1 cup has been added, mixing as the milk is added.

Add the egg yolk mixture to the sauce pan, increase heat to medium-high and stir constantly until the mixture reaches the desired consistency.

Once the mixture thickens, add the vanilla. Mix until well combined.

Remove the pot from the heat.

In a large bowl, combine the egg whites and the tablespoon sugar. Beat the egg whites until stiff. Fold the egg whites into the natillas in the pot.

Sprinkle cinnamon on the top.

Divide into serving dishes and serve while hot.

Put remaining natillas into the refrigerator and serve the next day, cold.