Put the oatmeal, sugar and raisins in a non-stick saucepan. Pour milk over it and mix everything well. Heat slowly over medium heat and allow to swell, stirring occasionally. After about 10 minutes, the porridge should have thickened a little. Otherwise you can increase the temperature a little so that the paste becomes thicker. Stir well again and again so that the porridge does not stick.
After about 15 minutes, the pulp should be so thick that bubbles form. As soon as the porridge has the desired consistency, remove the pan from the heat and pull the hazelnuts into the porridge.
Arrange in two deep plates and sprinkle with cinnamon sugar if you like.