First things first, lets make the bread dough; pop the milk into a microwaveable bowl or jug and heat in the microwave for 40-50 seconds until warm to touch but no boiling. Pour in the yeast and stir, leave for 5 minutes
Pour your milk mixture into a large bowl or the bowl of a free standing mixer fitted with a dough hook and stir in the sugar. Pop in the egg, melted butter and Vanilla Extract and mix together. Finally pour in the flour and salt and begin to bring the ingredients together.
Once the ingredients are combined begin to knead the dough on a lightly floured surface for 10 minutes or using a mixer knead on a medium speed for 8-10 minutes.
Pop your dough into a bowl lightly greased with oil and cover with cling film or a tea-towel and leave for about 1.5 hours to double in size.
Once your dough has risen, pop onto your work surface lightly dusted with flour and roll out to a rectangle approx. 12x10 inches.
Mix together the light brown sugar and cinnamon. Spread the softened butter over the top of your rolled out dough and sprinkle over your cinnamon sugar. Press the sugar mixture into the butter to help it stick and finally sprinkle over the Chocolate Chunks.
Starting with the longer edge of the dough roll up the dough and cut into 9 equal pieces.
Lightly grease and line a 11x9 inch deep baking tin and pop in your cinnamon rolls spaced equally apart. Cover and leave to rise for 30 minutes.
10 minutes before baking, preheat your oven to 190°C/170°C/Gas Mark 5. Brush your cinnamon buns with some milk and pop in the oven to bake for 30-35 minutes until golden brown and your buns have risen.
Whilst your cinnamon buns are baking, make your icing; mix together the icing sugar, water and Vanilla Extract until you have a smooth pourable icing.
Once baked leave your buns to cool for 10 minutes in the tin and then pop on a wire rack and drizzle over the icing using a spoon.
Your cinnamon buns are now ready to enjoy, they are best eaten fresh on the day they are baked!