Feed your starter in good time before it's time to bake.

Mix all ingredients, except butter and let the dough rest for an hour. Perform 3 or 4 sets of stretch and fold spaced out by 30 minutes. Make sure the dough passes the windowpane test.

Take out the butter from the refrigerator half an hour before it's time to mix it into the dough.

Add some pieces of butter and knead and pinch it into the dough. When you don't feel any lumps, add some more butter and repeat until all has been incorporated into the dough.

Let the dough bulk ferment until it has expanded by 30-50% in volume. Place the dough in the refrigerator for two hours if it has fermented in room temperature to make sure it hardens all the way through.

Dump out the dough on a lightly flourd surface and divide it into four piceces of equal size. Form the dough pieces into rounds.

Grease a bread tin abundantly with butter and squeeze the rounds into the tin.

Place the loaf and tin in a plastic bag an let it proof until it has doubled in size.

Pre-heat the oven to 420ºF/215ºC.

Brush the loaf with a beaten egg and a pinch of salt. Make sure that no egg mixture flows down between the loaf and the bread tin.

Bake for about 60 minutes or until inner temperature reaches 208ºF/98ºC. You may have to lower the heat or cover with aluminium foil at the end.

Remove bread from the bread tin as soon as it's cool enough to handle.