Mix flour, cocoa powder, sugar, salt, and yeast.
Add warm milk, eggs, and butter, and knead the dough.
Let the dough ferment for 1 hour.
Shape the dough into balls and place on a pan.
Allow the dough to ferment for a second time on the pan.
Bake in a preheated oven at 180°C for 20 minutes.
Cool on a wire rack.