Add the yeast to the warm water in a large bowl and mix in the honey and oil.
Slowly add the flour, bit by bit, stirring at first and then kneading once it is less sticky.
Add the cinnamon, vanilla extract and salt, and knead using a dough hook in a stand mixer for ten minutes.
Split the dough into two pieces, place one piece in a bowl and cover with clingfilm, then leave it to rise for an hour until doubled in size.
Take the other piece of dough and knead in the cocoa powder. If it goes a little dry you can add a tiny bit more water and/or oil, but make sure it is only a tiny amount.
Put the chocolate dough in a bowl, cover with clingfilm and leave to rise for an hour until doubled in size.
Knock back both bowls, then add half the chocolate chunks to each bowl and knead in to the dough.
Split each piece of dough into three and roll each piece into a long thin strand.
Braid the six strands to form a plait (check YouTube for tutorials on how to do thiand place the loaf on a silicone mat to rise again, for 30 to 45 mins (I left it for longer as I popped out but would reduce the time next time).
Preheat the oven to 180 degrees (fan). Brush all over the loaf with the egg wash.
Bake for 30 to 35 minutes or until the loaf is golden brown and the base sounds hollow if tapped. When you check the loaf you can also brush on more egg wash to cover any areas where the bread has stretched during baking, this gives a uniform shiny appearance.