Heat the three lightly heaped spoons of Nutella along with the milk over medium heat. Then it is best to stir with the whisk (approx. 2 minutes) until everything has combined nicely. At the end, add a pinch of cinnamon and see if the chocolate sauce has the desired consistency. If necessary, add a tablespoon of milk.
It is best to serve it warm with ice cream or a fruit salad, because it will become a bit firm again after cooling.