Place the flour in a large mixing bowl. Add the salt, sugar and yeast to the bowl, keeping the salt and yeast separate.
Add the warm milk, soft butter, eggs, orange extract and half the water. Mix the ingredients together until you have a soft dough. If it is too dry, add the remaining water slowly until you have a soft, but not soggy, dough. Knead for 5 mins in a mixer or 10 minutes by hand or until the dough is very smooth and bouncy.
Place the dough in a lightly oiled bowl, cover and leave to prove in a warmish place for at least 1-2 hours or until the dough is doubled in size.
Once the dough is ready, turn out onto a lightly floured work surface. Lightly flatten it out a little and place the orange zest and chocolate chunks on top. Gently work them into the dough until they are all evenly incorporated.
Place the dough back into the bowl and leave for one hour until risen in size again.
Divide the dough into twelve equal portions - if you want them all the same size you can weigh them - 75g is a good size.
Roll each piece of dough into balls and place fairly close together on a baking tray lined with baking paper.
Cover and leave to prove for 45-60 minutes until well risen and at least doubled in size.
About 30 minutes before proving time is done, preheat the oven to 200C.
For the crosses, mix 75g plain flour and 75-100ml water together until you have a smooth paste that isn't too runny. Using a piping bag fitted with a small nozzle, pipe crosses on the buns. Alternatively, you can drizzle the crosses over using a teaspoon.
Bake for 20-25 minutes or until the buns are golden brown. Remove the buns from the oven and brush the glaze over the buns immediately. Transfer to a wire rack.