Toasted Oat Walnut Dutch Oven Boule

Steps

1. Prep first: in a dry skillet over medium heat, toast 60 g of the oats for about 4 minutes until fragrant, then tip them into a small bowl. Toast the walnuts in the same skillet for 4 to 5 minutes, cool, and chop roughly. Keep the remaining 10 g of oats aside for the top.
2. Pour 30 g of the water over the toasted oats and let them soak while you mix the dough.
3. In a large bowl, whisk 420 g of the bread flour with the whole wheat flour, instant yeast and salt. Set the remaining 20 g of bread flour aside for dusting.
4. Stir the maple syrup into the remaining 340 g of water, pour it over the bread flour mixture and mix until no dry bits remain. This is about 77% hydration (counting all the water against the dough's bread flour and whole wheat flour) and 2% salt.
5. Cover and rest 30 minutes, then add the soaked oats and the walnuts and squeeze and fold them through until evenly spread.
6. Bulk rise covered at about 75°F (24°C) for 2 to 2½ hours, doing 3 sets of stretch-and-folds 30 minutes apart in the first 1½ hours, until the dough is about 75% larger, domed and bubbly at the edges.
7. Dust the counter with half of the reserved bread flour. Turn the dough onto it, shape it into a tight round, mist the top with water and press it into the reserved 10 g of oats.
8. Dust a towel-lined bowl with the remaining half of the reserved bread flour and set the dough in it seam side up.
9. Cover and cold proof in the fridge for 10 to 12 hours, until it springs back slowly when poked.
10. Place a lidded Dutch oven in the oven and preheat to 475°F (245°C) for 45 minutes.
11. Turn the dough onto parchment, score the top with a sharp blade and lower it into the hot Dutch oven. Bake covered 22 minutes.
12. Uncover, reduce to 450°F (230°C) and bake 20 to 25 minutes more, until deep brown and 205–210°F (96–99°C) in the center.
13. Cool the loaf on a rack for at least 1½ hours before cutting into 12 slices so the crumb sets and the crust stays crisp.