In a small saucepan over medium heat, combine 1 ½ cups of the milk with the cinnamon, vanilla bean, cloves, peppercorns, ginger, cardamom pods and a hefty pinch of salt. Bring the mixture to a simmer, then turn off the heat and let it stand for 15 minutes.
Strain the mixture through a sieve, discarding all of the solids except for the vanilla bean. Scrape the seeds from the vanilla bean into the milk; discard the vanilla pod.
Wipe out the saucepan and return the milk to the pan over medium heat.
Meanwhile, in a medium bowl beat the eggs with the sugar for two minutes, or until they are light and lemon colored. Add the heated milk in a stream, whisking gently.
Return the egg-milk mixture to the saucepan and cook over medium heat, stirring constantly with a wooden spoon, until it thickens and coats the back of the spoon, about four to six minutes. Do not let the mixture come to a simmer or the eggs will scramble.
Quickly add the remaining 1/2 cup of milk to the pan to stop the cooking. Transfer the mixture to a pitcher and chill for at least two hours or until very cold.
To serve, divide the eggnog among four chilled glasses, stir in a dash of brandy or rum, if desired, and top with a sprinkle of freshly grated nutmeg.