Add all dough ingredients to your bread maker (in the order I've laid out) and set the machine to make dough.
When the dough is ready, roll out on a floured surface until you have a rectangle of around 37cm x 52cm. Have the shorter side facing you.
Spread the butter evenly over the dough, leaving a narrow edge (around 1cm) all the way round. Combine the sugars and cinnamon and sprinkle over the butter, using your hands to evenly distributed the mixture.
Carefully begin to roll up the dough, pulling it fairly taut as you roll. Place the dough, seam side down. Cut into 12 rolls.
Place in a greased tin or dish leaving a little space in between.
For the overnight version, cover and place in the fridge. In the morning, pre-heat the oven to 200°C and allow the buns to come up to room temperature (I usually sit the dish on top of my oven as it's heating up). Sprinkle with the chocolate chunks and bake for around 20-25 minutes
If baking immediately, pre-heat the oven to 200°C. Cover the dish and leave to rest for around 30 minutes. Sprinkle with the chocolate chunks and bake for around 20-25 minutes.
Allow the buns to cool for a while. Prepare the icing by mixing the milk and vanilla essence together, then adding as much icing sugar as needed to make a thick paste. Drizzle or pour over the buns and eat warm. Enjoy!