I call this my chocolate tea. I use a really big mug (about 16oz), so adjust it down for a smaller one.

Use unsweetened cocoa powder (Hersheys is good).
2 teaspoons of cocoa
2 packets of sweetner
boiling water
mix it up and then add 1 or 2 tablesoons of heavy cream (kind of like when you have coffee light)

I have at least one mug of this every day....helps with the chocolate cravings. At first it seemed kind of thin when you are used to hot chocolate mixes....thats why I called it a tea, now I'm used to it. Yum