Put the wholegrain oat flakes in a bowl. Roast the hazelnuts dry in a small pan over medium heat, stirring occasionally. Allow to cool and coarsely chop in a lightning chopper. Usually it is enough to press the button three times.
Add the ground hazelnuts to the wholegrain oat flakes. Add the cocoa, mix everything and pour organic milk on top. Stir until the cocoa has dissolved.
You can grind and use the hazelnuts without roasting them. This creates a different taste.