Combine powdered sugar, cocoa powder, white chocolate, powdered milk, salt and cornstarch in a mixing bowl and incorporate evenly.
Working in batches, add the mix to a food processor and pulse until the white chocolate is finely ground.
Store mix in an airtight container for up to 3 months.
To make cocoa, mix 1/3 cup of the cocoa mix with 1 cup of hot water or milk.
Top with mini marshmallows.
Notes
Try More Chocolate: Add different chocolates to have a different flavor Add Candy: Try peppermint sticks, M& M's, caramel or butterscotch sauces. Add Some Booze: Try adding some Crème De Mint, Bailees, or your favorite flavor to make it a great after dinner treat for adults.