3:Separate the yolks from the whites, placing yolks in a large mixing bowl. Add the sugar and beat with an electric mixer until it is frothy. Add the milk-cornstarch mixture and beat until thoroughly mixed. Set aside.
4:Remove the lemon peel and cinnamon stick from the milk, using a slotted spoon.
5:Return the pot to the stove, heating on medium. After milk is hot, but not boiling, add the vanilla extract.

6:Begin pouring in the egg yolk mixture while beating with electric mixer on low.
7:Make sure that there are no lumps. Using a wooden spoon, stir continuously, so the milk does not stick.  Stir until mixture thickens up.
8:Pour natillas into 6 small bowls, ramekins, or large cups. If there are any lumps in the natillas, use a sieve to eliminate them.
9:Allow to cool to room temperature on the counter, then cover with plastic wrap and refrigerate until ready to serve. 

10:Sprinkle with ground cinnamon just before servings. Some cooks like to decorate with a Maria cracker, or pirouline (rolled wafer) cookie.