To make the dough warm the milk and butter in a saucepan, keep an eye on it to ensure it doesn't boil. When it reaches a simmer, stir in the orange peel and orange extract and remove from the heat.
Mix the flour, cocoa powder, yeast, sugar and cinnamon in a large bowl.
Add the wet ingredients to the dry and mix, adding a tsp of salt. Add the egg and give everything a good mix with a wooden spoon.
Tip the dough out onto a lightly floured surface and knead for around 10 minutes. You are looking for your dough to turn from sticky to smooth and elastic in texture.
Clean your mixing bowl and lightly oil it then return the smooth dough back to the mixing bowl. Cover with clingfilm and leave it to rise until it is double the size (about an hour)
Once doubled in size, turn the dough out onto a work surface and spread it out with your hands. Add the raisins, citrus peel and chocolate chips and work them into the dough by folding the dough and kneading them in.
Put the dough back into the mixing bowl, cover with clingfilm and leave to prove for another hour.
Line a large baking sheet with baking parchment and divide the dough into 15 equal pieces. Roll each piece into a ball shape using your hands and place on the tray in lines about a cm apart. They will rise and join together during baking. Cover with clingfilm and leave to prove until the buns have doubled in size (about an hour)
Preheat your oven to 190c/170c fan/gas 5