Parmesan Rosemary Country Sourdough Boule

Steps

1. The night before mixing (about 10 pm), feed your sourdough starter so you have at least 100 g; leave it at about 75°F (24°C). It should peak, doubled and bubbly with a domed top, in 4 to 8 hours, by the next morning.
2. Set aside 10 g of the bread flour for dusting; the remaining 450 g goes into the dough.
3. Autolyse: in a large bowl, mix the 450 g of bread flour, the whole wheat flour and 340 g of the water (all but 20 g) until no dry patches remain. Cover and rest 1 hour.
4. Add the sourdough starter to the dough and squeeze it in with wet hands until even, about 3 minutes. Rest 20 minutes.
5. Sprinkle the salt over the dough, add the remaining 20 g of water and pinch and fold until fully absorbed. This dough is about 72% hydration and 1.8% salt (about 75% hydration counting the starter).
6. In a small bowl, toss 80 g of the Parmesan with the rosemary and black pepper. Set the other 20 g of Parmesan aside for the crust.
7. Bulk rise at about 75°F (24°C) for 4 to 5 hours, covered. After the first 30 minutes, do the first set of stretch-and-folds and, while doing it, spread the Parmesan-rosemary mixture over the stretched dough and fold it in. Do 3 more sets of stretch-and-folds 30 minutes apart, then leave the dough undisturbed. Bulk is done when the dough has grown about 50%, feels airy and shows bubbles on the sides and top.
8. Turn the dough onto a clean, undusted counter, pre-shape into a loose round and rest 20 minutes uncovered.
9. Dust the top of the dough with half of the reserved bread flour and dust a banneton or towel-lined bowl with the other half. Flip the dough and shape a tight boule by folding the edges to the center and rolling it to build surface tension. Place it seam side up in the banneton.
10. Cold proof covered in the fridge for 12 to 16 hours, overnight.
11. The next morning, place a Dutch oven with its lid in the oven and preheat to 500°F (260°C) for 45 minutes.
12. Turn the cold dough onto parchment, mist or brush the top lightly with water and scatter the reserved 20 g of Parmesan over it. Score one deep slash or a cross with a sharp blade.
13. Lower the dough on the parchment into the hot Dutch oven, cover and reduce heat to 460°F (238°C). Bake 20 minutes.
14. Remove the lid and bake 22 to 28 minutes more, until the crust is deep mahogany brown and the center reaches 205–210°F (96–99°C).
15. Cool the boule on a rack for at least 2 hours before slicing into 12 slices.