In a bowl, add the 20g of dry yeast, the warm milk and the sugar, mix well. Add the salt, the eggs, the butter and mix very well again. Add 300g of flour, mix, add another 300g of flour and mix well. Set 100g of wheat flour aside and add the rest to the dough, mix very well by hand.
When the dough is no longer sticking to the bowl, remove and start kneading on a flat surface, for about 5 minutes.
Let it rest for 40 minutes.
Stretch out the dough on a flat surface into a circular shape, cut it into larger strips, then cut these strips into smaller pieces.
Stretch out one of these pieces into a thin log and put its ends together, twist the dough and put the ends together again.
Sprinkle some flour on a baking sheet, add the buns and let them rest for another 30 minutes.
Brush them with a mixture of egg yolk and milk. Bake in a preheated oven at 250°C (482°F) for 15 to 20 minutes.
Brush with butter as soon as you remove them from the oven.