How to make
In warm water, dissolve the yeast, sugar, salt and 1-2 tbsp flour, leave to effervesce. With a mixer beat the milk, eggs, yoghurt, oil and effervescent yeast. Then gradually add the flour. Knead a medium soft dough, leave it to rest for 10-15 min.
Divide the dough into 4 equal parts, form them into balls. Roll out each ball to a sheet about 9 1/2″ (24 cm) wide. Smear with the soft butter. Place another sheet, rolled out to the same size, on top, smear it and repeat with the final 2 sheets but don't smear the final one.
Place a small brandy glass in the middle of it (to help you see where to cut from). Cut it into 8 parts starting from the middle, then cut each of those into another 3 and weave them together. Repeat this process for the other parts. Cut with a knife all the way through in between them to separate the 8 parts.
Arrange them next to each other in a tray smeared with butter. Leave to rise, then smear with the yolk. Bake in a preheated 340°F (170 °C) oven until golden.