Put the milk in a saucepan with the cinammon stick and heat. Save a small glass of cold milk.
Beat the egg yolks with the sugar. Dissolve the cornflour in the cold milk, stir well and then add to the eggs and sugar.
When the milk is starting to boil, remove the cinammon stick and add the mixture of flour, milk, eggs and sugar. Stir well over the heat until the custard thickens. Don't boil.
Put the natillas into individual bowls or dessert glasses. Sprinkle with a little cinammon powder.
Tips and ideas: Spanish natillas