Spelt Cheddar Parmesan Sourdough Batard

Steps

1. The night before mixing (about 8 pm), feed your sourdough starter with its usual feed at equal weights; at about 75°F (24°C) it peaks, doubled and bubbly, in 8 to 12 hours, by the next morning.
2. Next morning, mix the spelt flour, the bread flour and all but 20 g of the water until no dry patches remain. Cover and rest 30 minutes.
3. Add the sourdough starter, the salt and the remaining 20 g of water, squeezing and folding until fully combined. Counting the starter, the dough is about 73% hydration and 2% salt.
4. Bulk rise covered at about 75°F (24°C) for 4 to 5 hours. Spelt is delicate, so do 3 gentle sets of stretch-and-folds 30 minutes apart in the first 90 minutes.
5. With the second set of folds, scatter the cheddar cubes, half of the Parmesan and the black pepper over the dough and fold them in. Bulk is done when the dough has grown about 50%, looks domed and jiggles.
6. Turn the dough out, pre-shape into a round, rest 20 minutes, then shape into a tight batard and set it seam side up in a parchment- or towel-lined banneton or bowl.
7. Cover and cold proof in the fridge 12 to 16 hours overnight.
8. The next morning, put the Dutch oven in the oven and preheat to 475°F (245°C) for 45 minutes.
9. Turn the cold dough onto parchment, brush lightly with a little water from the tap, sprinkle with the remaining half of the Parmesan and score one long slash.
10. Lower it into the hot Dutch oven, cover and bake 20 minutes. Uncover, reduce to 450°F (230°C) and bake 22 to 25 minutes more, until the crust is deep brown and the center reads 200–205°F (93–96°C).
11. Cool on a rack at least 2 hours before slicing into 12 slices for sandwiches.