1. Combine first 3 ingredients in a heavy saucepan over medium-high heat. Scrape seeds from vanilla bean; add seeds and bean to milk mixture. Heat milk mixture to 180° or until tiny bubbles form around edge (do not boil).
2. Combine sugar, bourbon, nutmeg, and egg yolks in a bowl, stirring with a whisk. Gradually add half of hot milk mixture to egg mixture, stirring constantly with a whisk. Return milk mixture to pan. Reduce heat to medium. Heat mixture to 160°, stirring constantly. Discard vanilla bean and cinnamon stick. Pour mixture into a bowl, and place plastic wrap on surface of custard. Chill thoroughly.
3. Pour mixture into the freezer can of an ice-cream freezer; freeze according to manufacturer's instructions. Spoon ice cream into a freezer-safe container; cover and freeze 8 hours or until firm. Garnish with freshly grated nutmeg, if desired.