Pour all ingredients into a saucepan. Heat over medium heat.
Whisk constantly until hot. Pour into a mug and sprinkle more cinnamon on top.
Notes
You can use a milk frother or blender to get the milk frothy. If you use a blender, make sure to cover the lid.You could also use a Nutribullet, but not with hot liquids. Froth a small amount of cold liquid and add it to the hot liquid.