Boil the espresso and set aside 1 2/3 tbsp (25 mL) of it. Add a little sugar if desired.
Pour the milk into a cup and make the foam using a foam maker.
If you don't have one, beat the milk in a stainless steel container so it doesn't mix with any other flavors or aromas.
Beat the foam until it becomes homogeneous and smooth.
Pour the espresso into the cup with the foamy milk and serve the cappuccino with a pinch of cinnamon if desired.