Must disagree w/ Green and Blacks, in regard to the order in which they assemble ingredients.

Tryng to mix cocoa powder with milk, cream and other stuff, and then later adding "sugar to taste," is a sure recipe for LUMPS. The trick is to mix dry cocoa with sugar first, stirring thoroughly to break down all lumps in the cocoa while it's still dry. The sugar should be granulated, with nice sharp corners on every grain; powdered (confectioner's) sugar won't do the job as well.

Then add, and do, whatever you please.

Slight topic shift: The Mexican "hockey-puck" chocolate that I've seen (complete and pre-mixed solid stuff, to be dissolved in hot milk) is called "Abuelita" brand ~ Espanol for "Grandma's" ~ and the yellow-and-red package has a picture of Grandma right on it. Great stuff!