Whisk the milk vigorously with the sugar, vanilla sugar, salt, orange rind and flour. Then stir over a low heat and bring to the boil once. Stand the pan in a bowl of iced water and leave to go cold. Butter four soufflé dishes approximately 6-7 cm in diameter (alternatively you can use cups of the same size) and sprinkle with breadcrumbs. Separate the eggs and beat the egg yolks into the cooled mixture.