In a large bowl, mix the yeast in the water until dissolved. Slowly add the flour and knead to form a dough. Add salt and knead again. Cover with cling film and leave to prove in the oven (switched off with light on) for 3 hours.

Remove and knead again. Shape into a circle and place on a baking tray lined with parchment paper. Cover again and put back in the switched off oven for another hour.

Remove from oven and preheat to 220 degrees Celsius. Make a criss cross on top with a knife. Sprinkle with a little flour.

Bake for 10 mins at 220 then turn the heat down to 200 for another 15 mins. Leave to cool on a wire rack