Split the vanilla bean and scrape out the seeds, set aside.
In a bowl over simmering water, whisk together the eggs, sugar and vanilla bean seeds. Keep whisking until a ribbon is formed and the mixture has been heated to 140 degrees. Hold it at this temperature for 2-3 minutes, and allow the mixture to thicken. Stir this mixture into the milk. Stir in the cinnamon.
Refrigerate this for 2 hours or until cold. Whip the cream and add it to the egg mixture. Sprinkle the top with the mace before serving.