Roughly chop the chocolate. Wash oranges thoroughly and rub dry. Remove zests from 1/2 orange with a zest ripper. Cut oranges in half and squeeze. Bring milk and vanillin sugar to the boil.
Add pasta and sugar. Cook over medium heat stirring frequently for 12-15 minutes. Drain the noodles and collect the milk. Heat 100 ml orange juice, chopped chocolate and 250 ml of the vanilla milk over low heat, stirring occasionally.
Roast the pistachios in a pan without fat. Leave to cool, then chop roughly. Stir the sauce thoroughly at the end. Arrange sauce and noodles and sprinkle with chopped pistachios. Decorate with orange zests.