Pour the milk into the casserole dish and add the Nutella, cocoa powder, caster sugar and semolina. Over a medium heat stir with a silicone spatula or wooden spoon until the ingredients dissolve completely. Allow the mixture to come to the boil then simmer for two minutes stirring all the time.
Bake the chocolate semolina pudding in the oven with the lid on for 15 minutes then take the casserole out and reduce the temperature to gas 3 / 160c.
Meanwhile using an electric mixer beat the egg whites to a foam then gradually add the rest of the caster sugar and beat until you have a soft peak meringue. Fold in the finely chopped hazelnuts and use the spatula to spread the meringue over the chocolate semolina pudding.
Bake for 15 minutes until nicely golden on top, scatter over a few roughly chopped hazelnuts and serve.