Place the chocolate chips (or chopped chocolate) in a food processor. Pulse in short bursts until the chocolate is ground into fine crumbs. Do not over-process or it will melt.

Add the powdered sugar, cocoa powder, dry milk powder, cornstarch, and salt to the food processor.

Pulse the mixture several times until all ingredients are evenly combined and the color is uniform.

Transfer the mix to an airtight container or glass jar.

To serve: Stir 1/3 cup of the mix into 1 cup of hot water or hot milk. Whisk well until dissolved. Top with marshmallows or whipped cream if desired.