Italian Hot Cocoa

When I need a chocolate experience, I'll put together what I'm told is
an Italian-style hot cocoa. I initially saw the recipe in the middle of
an article in The New Yorker, which went something like this. (Sorry
that I don't know the by-weight equivalents.)

Mix
1/2 cup cocoa powder
1/3 cup white sugar
1 teaspoon cornstarch
with
1/4 cup water
in a saucepan over medium heat, stirring constantly. Once this
mixture comes to a boil, add 2 cups of liquid (water, brewed coffee,
skim milk; the author recommended a cup of water and skim milk each)
and stir over heat until heated through and mixed.

This produces a thick, quite rich brew, not for children, but highly
chocolate-concentrated. Clearly, it's pretty much just empty calories,
but not that much of them, and the fat is only what comes in your cocoa.