I buy Abuelita brand hot chocolate discs.
The box comes with 5 thick discs of chocolate that already has cinnamon & sugar added & "pre-scored" into wedges. I think one wedge is supposed to equal to 2 mugs of hot chocolate with the milk measurement, but I always add extra.

The discs are pretty much rock hard, though, so you kinda have to use a grater & grate it into shavings, or use a knife and grate it up that way.

And then you heat up the milk in a small pot, add the chocolate, and stir it until the chocolate melts & combines with the milk.

Sounds like a lot of work, but it isn't, and it's worth it. I do love adding a couple or 3 big puffy marshmallows on top and stirring them in to mix with the rest.... Soooooo yummy!!