Warm the milk lukewarm. Crumble the yeast, mix with 1 teaspoon sugar and milk. Leave in a warm place for about 10 minutes
Place fat, salt, flour, egg, 5 tablespoons sugar and vanillin sugar in a bowl. Add the yeast mixture and knead with the dough hooks of the hand mixer to a smooth dough. Cover and leave to rise in a warm place for about 45 minutes. Grease a box form (approx. 30 cm long, approx. 2.8 litres capacity) and dust with flour
Form the dough into a roll on a floured work surface and divide into 4 pieces. Form dough pieces into smooth balls and place them next to each other in the box mould. Cut the dough balls in the middle along the length of the mould with scissors once each. Cover and let rise for about 1 hour
Whisk the egg yolk and 3 tbsp. water. Spread the brioche with it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 30 minutes. Reduce temperature (electric oven: 175 °C/ convection oven: 150 °C/ gas: level 2) and bake for another 30 minutes. Finally cover with aluminium foil if necessary
Remove the brioche, cover with a tea towel and let it cool on a cake rack for 20-30 minutes. Turn the brioche out of the pan, turn it over and cover and let it cool. Serve with butter and jam
waiting time approx. 2 1/4 hours