This easy, tasty loaf is carved with a gorgeous design that needs a razor-sharp knife to create. Professional bakers use a Landaise Lame or Grignette – which is rather like a razor blade inserted into a plastic safety handle – but a very sharp artist’s scalpel can do the job.
Place both flours in a stand mixer fitted with the dough hook. Add the yeast, salt and rosemary and stir on low speed for a few seconds. Add 325ml of hand-hot water and mix again on low until you have a soft dough (you may need up to an extra 25ml of water). Keep mixing for a further 5 minutes (or turn out the dough onto a floured work surface and knead for 10 minutes), until the dough is smooth and elastic.
Place the dough in a lightly oil a large, clean bowl, cover the bowl with oiled cling film and leave in a warm place or proving drawer to rise for about 1¼ hours, or until the dough is at least doubled in size.
Turn out the dough onto a work surface and knock it back. Knead it lightly into a large boule shape and place it on the lined baking tray. Place the tray inside a large plastic bag, ensuring the dough doesn’t touch the bag, and leave the dough to prove in a warm place or proving drawer for about 40 minutes, or until well risen.
Heat the oven to 220°C/200°C fan/425°F/Gas 7. Pop the roasting tin in the bottom of the oven.
Liberally dust the dough with white bread flour to give a good coating. Using the scalpel or bread-scoring knife, score a lily (or other flower design, if you prefer) into the surface.
Place the loaf in the oven, pour 100ml of water into the roasting tin and immediately close the door (this generates steam to give you a good crust). Bake for about 25 minutes, then slide the dough off the baking tray onto the oven rack and return it to the oven to bake for a further 15 minutes, until the bottom is crisp and the base sounds hollow when tapped. Place on a wire rack to cool.