Put the milk, the yeast and powdered sugar in a bowl and mix with a fork.
Add the eggs and mix until the ingredients are homogenized.
Then add salt, flour, butter and mix with a fork. When the dough begins to form, continue mixing with your hands.
Transfer the dough to a bowl, cover with wrap and leave it 6-12 hours to rest.
Preheat the oven at 190° C in fan mode.
Remove the dough from the bowl and put it on your workbench. The dough will be soft and will stick a little bit in your hands. If it sticks a lot and you can not shape it, use a little flour.
Split into 12 pieces and shape balls.
Butter and put flour to 2 muffin molds and put one piece in each case.
Spread with egg yolk diluted in water, cover with a towel and leave for 30 minutes to rise.
Bake for 25 minutes until they get a golden color.