Break open cardamom pods with the back of a knife.
In a medium saucepan heat the milk + cardamom. Right when you see the milk about to simmer remove it from heat. Let cardamom infuse in the milk for 20-30 minutes.
When the milk has infused remove the cardamom pods from the milk.
Cornstarch slurry: In a small bowl add cornstarch and a splash of the infused cardamom milk. Mix with a spoon.
In a medium saucepan over medium heat place chopped chocolate + cocoa powder + sugar + a splash of infused cardamom milk. Whisk until melted.
Slowly whisk in the rest of the infused cardamom milk. (If you like a thinner hot chocolate you could essentially stop here, but if you like a thicker hot cholate continue to the next step).
Whisk in the cornstarch slurry. Keep whisking until the mixture has thickened, 2-3 minutes.
Garnish with chopped milk, white, and dark chocolate. Or try some marshmallows or whipped cream.
Serve hot. If mixture cools down too much, warm again adding a bit of milk to thin it out.