Put the flour, salt, yeast and butter into a large bowl and mix together. Add nearly all the water and blend the ingredients together, then add the remaining water and mix in the bowl for 2 minutes.

Tip the dough out onto a lightly floured surface and knead well for 5 minutes, then place the dough back in the bowl and leave to rest for 2 hours.

Line a baking tray. Shape the dough into a ball, place on the baking tray and leave to rise for 1 hour.

Preheat the oven to 220°C/425°F/gas mark 7. Using a sharp knife, slash the dough across the top and dust with flour. Bake for 30 minutes until golden brown, then transfer to a wire rack to cool.