Measure the milk and reserve about half a cup in a jar. Heat the rest in a small pot with a pinch of cinnamon.
Add the cocoa and cornstarch to the milk in the jar and stir well. If the mixture is too thick, add a bit of the milk being heated.
Once the milk boils, pour the cocoa and cornstarch mixture and stir with a whisker until it boils again. Once that happens, turn off the heat and add the strawberries and brandy.