In a saucepan, combine the milk, evaporated milk and vanilla and warm up over a low heat.
Combine the cocoa powder, sugar, cornstarch and cinnamon in a small bowl. Whisk into the warm milk mixture, stirring frequently to prevent it from scorching.
Remove the hot chocolate from the heat just after it has come to a boil. The mixture should be suuuuuper rich and thick!
Cook's Note: For grown-up kids, a shot of brandy, Kahlua, or peppermint schnapps is really yummy!