On the day before baking sift the flour into a bowl and mix with yeast and water. Cover and leave in the fridge for at least 8 hours (better: overnight).
Take the starter dough out of the fridge one hour before preparing the dough.
For the dough, stir the fresh yeast into the water and add the butter. Sift in the flour and salt and stir.
Add the starter dough and knead the dough for 10 minutes.
Place the dough on a dusted work surface, cover and leave for the first proof of 30 minutes.
Grease and flour the bread tin (25cm) and preheat the oven for 230°C (including a baking tray with water).
Shape the dough and place into the bread tin, sprinkle with some flour, cover and leave for the second proof of 30 minutes. After the first 10 minutes cut the dough lengthways (1-2cm deep).
Take out the baking tray and bake the bread for 15 minutes. Change the temperature to 210°C and bake for another 30 minutes.