Combine whole wheat flour, yeast, sugar, and salt in a bowl and mix.
Add warm milk and butter, then knead the dough.
Let the dough rise for 1 hour (first fermentation).
Divide the dough into 6 portions, roll out each piece with a rolling pin, place salted butter inside, then roll up and shape.
Put them on a baking tray and let them ferment for another 30 minutes (second fermentation).
Brush egg wash on the surface and sprinkle salt on top.
Bake in a preheated oven at 180°C for 20 minutes.