Fill a cocktail shaker about half full with cubes of ice.
Pour 10-12 ounces (about the amount that your coffee cup holds) of brewed coffee into the shaker over the ice. Add any sweeteners and milk that you'd like.
Cover the shaker with both lids. Shake the dickens out of it, at least 20 seconds. Shake until you feel the cold through the metal of the shaker and until it starts to make your hand cold.
Once you can’t shake any more, remove the top lid and quickly pour into a tall glass. Be sure to let the foam come out and top your coffee. Garnish with a shake of cinnamon or a cinnamon stick if desired.