Combine flour, sugar, salt, and yeast in a bowl and mix.

Make a well in the center and add the milk, oil, and egg white, kneading into a soft dough.

Cover the dough and let it proof for 1 hour.

Take small portions of the dough, fill each with chocolate, and shape into balls.

Place the prepared pastries on a baking tray lined with parchment paper and brush with egg yolk.

Bake in a preheated oven at 180°C (350°F) for 20-25 minutes until the tops are golden brown.