Mix the flour, sugar, salt and yeast together in a large bowl. Make a well in the centre of the mix and add the water. Using your fingers, gradually mix all the dry ingredients into the water until it makes a dough.
Remove the dough from the bowl and put on a lightly floured surface. Knead the dough for 5 minutes then put into a clean bowl, cover with a warm, damp cloth and leave somewhere warm to prove for about 40 minutes, or until doubled in size.
Once proved, remove from the bowl and knead for another minute or two.
Split the dough into 3 equal pieces and stretch the dough out so you have 3 strands that are approximately 90cm in length and flatten slightly with your fingertips.
Chop your chestnuts up into small pieces and slice your pancetta into 5cm long strips. Scatter chestnuts and pancetta down the centre of each strand of dough – saving some for the top of your plait – then fold each piece of dough over so the chestnuts and pancetta are inside the dough and loosely twist.
Place the strands next to each other in a line and join one end together. Then plait the dough and join at the other end.
Grease a large baking tray with olive oil and place the wooden carton from the camembert in the centre – leave the camembert in the fridge for now.
Carefully transfer the plait to the baking tray, placing it around the carton (leaving 1cm space between the carton and the dough) to make a wreath and press the ends together to join.
Cover with a warm, damp tea towel and leave to prove in a warm place for 15 minutes.
Preheat the oven to 200°C/Fan 180°C/Gas 6. Once proved, place the leftover chestnuts, pancetta and springs of rosemary on top of the dough.
Remove the top layer of rind from the camembert, leaving a 1cm rim around the edge, and place in the carton on the tray with a sprig of rosemary in the middle. Drizzle the dough with olive oil and place in a preheated oven for 25-30 minutes or until golden brown.
Place in the centre of your table and eat whilst the camembert and bread are still warm.