Parmesan Black Pepper Walnut Rye Batard

Steps

1. Day 1, morning: give your sourdough starter its usual 1:1:1 feeding by weight and leave it at about 75°F (24°C). It should double and peak, domed and bubbly, in 4 to 6 hours.
2. While the starter rises, toast the walnuts in a dry skillet over medium heat for 4 to 5 minutes, stirring, until fragrant. Cool completely, then chop roughly.
3. When the starter peaks, stir the molasses into the water in a large bowl until dissolved, then whisk in the sourdough starter.
4. Add the rye flour and the bread flour and mix with a wet hand or stiff spatula until no dry patches remain. Cover and rest 30 minutes at about 75°F (24°C).
5. Sprinkle the salt and black pepper over the dough and squeeze them in with wet hands. Add the walnuts and the first portion of Parmesan (the 70 g for the dough) and fold until evenly spread. The dough will be sticky and paste-like, which is normal for rye. This works out to about 82% hydration and 1.4% salt, counting the starter's share of water and grain.
6. Bulk rise, covered, at about 75°F (24°C) for 3 to 4 hours. During the first 90 minutes, do 3 sets of gentle stretch-and-folds with wet hands, 30 minutes apart. Bulk is done when the dough has grown by about half and shows small bubbles on the surface and sides.
7. Wet your hands and work surface lightly. Turn out the dough, press it into a rough rectangle, roll it up tightly into a batard about 9 inches long, and pinch the seam closed.
8. Spread the remaining portion of Parmesan (the 20 g for the crust) on a plate. Mist or brush the top of the batard with water and roll it top-side down in the Parmesan to coat. Place it seam side up in a parchment-lined oval basket or loaf pan.
9. Cover and cold proof in the fridge overnight, 12 to 14 hours. It is ready when it has risen slightly and small cracks appear on the surface.
10. Day 2: place a Dutch oven with its lid in the oven and preheat to 475°F (245°C) for 45 minutes.
11. Turn the batard onto a piece of parchment, cheese side up, and score one shallow line down its length. Lower it into the hot Dutch oven, cover, and bake 20 minutes.
12. Remove the lid, reduce the oven to 450°F (230°C), and bake 25 to 30 minutes more, until the crust is deeply browned and the center reads 205 to 210°F (96 to 99°C).
13. Cool the loaf on a rack for at least 4 hours before slicing so the rye crumb sets, then slice thinly into 12 pieces for sandwiches.