Heat your milk and water slightly, it should be warm, not hot! you should be able to dip your finger in it without burning yourself. Add in your butter,egg ,sugar and yeast into the milk and water and let the yeast bloom for a few minutes.
In a separate bowl combine your flour and cacao powder. Then slowly add in your liquid to the dry stirring as you go until you start to get a shaggy dough.
Fold your chocolate pieces into the dough. Tip the dough out on to a lightly floured surface and knead for about 10 minutes until the dough becomes a smooth dough ball.
Place the dough into an oiled bowl, cover and let sit in a warm place like your microwave or oven for 1.5/2 hours or until doubled in size.
Once your dough has doubled in size punch it down and tip onto a floured surface divide the dough into quarters and then each quarter into 4. Shape each dough section into a ball and place on a tray lined with baking paper seam side down. Once each ball is done cover with a damp cloth. Let rise for a further 1 hour.
While you’re waiting for the bread rolls to rise preheat the oven to 350 degrees Celcius.
After one hour your individual buns should have raised. Place them in the oven on the middle shelf and turn the heat down to 300 degrees. Place a tray of cold water or a couple of ice cubes at the bottom of the oven to produce steam for the bake. Bake until well risen about 16 minutes tap the base and they should sound hollow.
Let them cool on a cooling rack for about 30 minutes and then they're ready to go. Best enjoyed freshly baked, sliced in half with a little bit of butter.