To make the dough, separate the egg yolk from the egg white. Heat the milk in a pan until lukewarm. Knead together with the yeast the flour, milk, sugar, egg yolk, butter and salt into an elastic dough until the surface is smooth and no longer sticky. Place the dough in a clean bowl, cover with a dish towel and leave to rise for around one hour at approx. 30-35°C until it has doubled in size.
Knead the dough again and shape into a round loaf. Preheat the oven to 180°C. Position the bread on a baking tray lined with baking paper and use a knife to mark it with a cross approx. 5 mm deep. Brush with egg white and bake for approx. 30 minutes.