Heat the milk in a saucepan on a medium to high heat, adding the cinnamon bark and vanilla essence at the beginning.
When boiling point is reached, reduce the heat to a minimum, stir and simmer for 10 minutes with the lid off.
Turn off the heat and remove the cinnamon. Add a good tablespoon of cocoa powder and stir in. Filter the milk, wash the saucepan before returning the milk. Turn the heat back on.
Add a pinch of sugar and a pinch of salt. Add the chocolate pieces and stir in gently until the mix is smooth and silky.
The chocolate can then be served, but if a thicker mix is desired, keep cooking until the desired consistency is reached.