Initial sponge: mix together

250 lively sourdough culture (100% hydration)

150g type 55 flour

150ml water

Cover and leave to make a sponge.

Add:

2 eggs

5g salt

100g Parmesan, grated finely (or more for a stronger

400g type 55 flour

Knead for a few minutes until all the ingredients are well mixed and the dough has come together. Allow to rest for 30 minutes and knead again. Repeat this process 2-3 times until you have a soft dough. Leave in a covered bowl to bulk prove. Shape into a round, put into a floured banetton with the seam on top and place in a polythene bag and leave overnight in the fridge. Prior to baking brush with beaten egg and sprinkle with more grated Parmesan. Cook in a very hot oven under a preheated cloche for 35-40 minutes.