1. Combine milk, lemon peel and cinnamon stick. Heat in a saucepan. In a bowl, combine sugar, cornstarch and egg yolks, whisking well. Slowly add hot milk mixture to sugar mixture, whisk well. Return mixture to saucepan and cook over low heat until mixture thickens. Cool 5 minutes and pour mixture in a shallow gratin dish. Chill. To serve, sprinkle with sugar and burn with a torch until sugar is caramelized. It hardens as it cools.