In a large bowl, whisk together all ingredients until well incorporated. This can be done in a food processor also, but you'll have to process smaller amounts of the ingredients at a time.
To make a mug of cocoa, place 1/2 cup of the mix into a large mug. Bring a cup (8 oz.) of water or milk to a boil. Pour water over the dry mix and whisk with a small whisk until well blended and frothy. Garnish with whipped cream and a sprinkle of cinnamon. Marshmallows and a candy cane stirrer are also fun add-ins.