Pour some of the skim milk into a mug or small mixing bowl and mix with the starch. Heat the rest of the skim milk with the sugar.
Gradually add the cocoa to the hot skim milk and bring to the boil. Remove the boiling skim milk from the heat, add the dissolved cornstarch and bring to a boil while stirring as before.
Pour into pudding molds rinsed with cold tap water and set aside to cool for several hrs.
Tip: Feel free to use better chocolate – the more delicious the result!