Mix all ingredients in a stand mixer with dough hook; knead 10–15 minutes until soft, supple, and stretchy.
Form into a ball, place in an oiled bowl, and cover with plastic wrap or a damp towel. Bulk rise 5–7 hours at 27°C (80°F).
Once doubled, turn dough onto a floured surface. Divide in half, letting one rest while you work the other.
Stretch into a thin rectangle. Evenly sprinkle chopped walnuts and drizzle honey on top. Fold like a letter, then fold again top-to-bottom. Spin to tighten surface tension.
Place seam side up in a floured banneton, cover, and refrigerate overnight.
Next day, preheat Dutch oven at 250°C (500°F) for 1 hour.
Turn dough onto parchment, score the top, and place into hot Dutch oven.
Bake 20 minutes covered, then 15–20 minutes uncovered at 235°C (450°F).
Cool fully on a wire rack before slicing.