Chop the chocolate coarsely with a knife and set aside.
In a bowl, activate the yeast by mixing it with the milk and sugar. Leave to dilute for 15 minutes. The milk should not be cold but at room temperature.
Once the yeast has been activated and diluted, add the mixture to the flour.
Mix in a food processor at low speed and add the salt in a second step.
Add the butter and leave to knead for a good 5 minutes.
Cover and leave to rise for at least 1 hour (ideally 1h30-2h)
Preheat the oven to 190 °C.
When the dough has finished rising, add the chocolate chips to the dough and form dough pieces of equal weight.
Place the rolls on a baking tray, brush with egg yolk and bake for 20-30 minutes. Enjoy!