In a medium saucepan, combine the milk, heavy cream, sugar, vanilla extract, and the seeds from the vanilla bean along with the pod itself. Heat over medium heat until just steaming, but do not boil. Stir occasionally to dissolve the sugar.
In a bowl, whisk together the egg yolks until they become pale and frothy.
Gradually add the hot milk mixture to the egg yolks, whisking constantly to temper the yolks and avoid scrambling them.
Return the mixture to the saucepan and cook over medium-low heat, stirring constantly, until it thickens slightly and coats the back of a spoon (about 5-7 minutes).
Remove from heat and stir in the ground nutmeg and cinnamon. Let the mixture cool slightly, then strain through a fine mesh sieve into a pitcher to remove the vanilla pod and any cooked egg strands.
Refrigerate the eggnog for at least 1-2 hours or until chilled.
To serve, pour the chilled eggnog into glasses, top with a dollop of whipped cream, and sprinkle with additional nutmeg or cinnamon for garnish.