In a large bowl, sift the confectioner’s sugar, then the unsweetened cocoa, to get rid of any lumps. Stir in the powdered milk, and whisk well until everything is combined. Add mini marshmallows to the container, if desired. This can be kept in the pantry for 6 months.When you want to make hot cocoa, combine equal parts hot cocoa mix and hot water. I like to put the hot cocoa mix in the cup and add the hot liquid on top, and stir, in order to not get any lumps. Enjoy!