Combine all ingredients in the bowl of a food processor.
Pulse or run until the chocolate bar pieces are completely broken down and the hot cocoa mix is a consistent powder.
Package in a container with a lid.
To serve, mix two tablespoons of hot cocoa mix with 6-8 ounces of hot water or milk, stir, and enjoy.
For the best results, include cornstarch in the mixture as listed in the ingredients. To serve, heat 2 tablespoons per 1 cup of milk over the stovetop until the mixture reaches a simmer. Stir constantly, and allow to simmer for 1 minute. Hot cocoa will thicken slightly. Serve.