Instructions

• Make the biga (preferment): In a large bowl stir together 2 cups (312 g) bread flour, 1 cup (240 ml) warm water (100–110°F / 38–43°C) and ½ teaspoon instant/rapid‑rise yeast until a uniform mass forms, about 1 minute. Cover the bowl tightly with plastic wrap and let stand at room temperature 8 to 24 hours.
• Make the soaker: In a separate large bowl stir together 3 cups (468 g) whole‑wheat flour, ½ cup (57 g) wheat germ and 2 cups (480 ml) whole milk until a shaggy mass forms, about 1 minute. Lightly dust a work surface with the bread flour (from the ingredient list) and turn the soaker out onto it. Knead the soaker 2 to 3 minutes until it is smooth. Return the soaker to the bowl, cover tightly with plastic wrap and refrigerate 8 to 24 hours.
• Assemble the dough: Tear the chilled soaker into roughly 1‑inch pieces and place them in the bowl of a stand mixer fitted with the dough hook. Add the biga, ¼ cup (85 g) honey, 4 teaspoons table salt, 2 tablespoons instant/rapid‑rise yeast, 6 tablespoons softened unsalted butter and 2 tablespoons vegetable oil. Mix on low speed until a cohesive mass starts to form, about 2 minutes. Increase mixer speed to medium and knead until the dough is smooth and elastic, about 8 to 10 minutes.
• Brief hand knead and first rise: Turn the dough out onto a work surface dusted with bread flour and knead by hand 1 minute (use the extra whole‑wheat flour if the dough is very sticky). The dough will be soft and slack. Transfer it to a large clean lightly oiled bowl, cover tightly with plastic wrap and let rise at room temperature 45 minutes.
• Perform stretch‑and‑folds and second rise: Lightly flour your fingertips. Deflate the dough by gently pressing the center, then perform 8 folds in the bowl: lift one edge and fold it toward the center, rotate the bowl 90° and fold again — repeat until you have folded 8 times total. Cover the bowl and let the dough rise at room temperature until doubled in volume, about 45 minutes.
• Shape and final proof: Adjust oven racks to the middle and lowest positions and place a baking stone on the middle rack. Spray two 9×5‑inch loaf pans with nonstick spray. Turn the dough out onto a well‑floured work surface (use the bread flour for the surface) and divide into 2 equal pieces. Working with one piece at a time, pat it into an 8×17‑inch rectangle (short side nearest you). Roll the dough from the short side toward you into a tight cylinder, tucking the roll under itself as you go. Turn the loaf seam side up and pinch the seam closed, then place seam side down in a prepared loaf pan, pressing gently into the corners. Repeat with the second piece. Cover the loaves loosely with plastic wrap and proof at room temperature until almost doubled and the tops rise about 1 inch above the pan edge, 60 to 90 minutes.
• Steam and bake: Place an empty metal baking pan (not glass) on the bottom oven rack. Bring 2 cups water to a boil on the stove. Just before baking, use a sharp serrated knife or single‑edge razor blade to make a single ¼‑inch‑deep slash lengthwise down the center of each loaf. Carefully pour the boiling water into the empty pan on the bottom rack to create steam, and immediately place the loaves on the preheated baking stone on the middle rack. Reduce the oven temperature to 350°F (177°C). Bake 40 to 50 minutes, rotating the loaves 180° and side to side halfway through, until the crust is dark brown and an instant‑read thermometer registers 200°F (93°C) in the center.
• Cool and store: Transfer the pans to a wire rack and let cool 5 minutes. Remove the loaves from the pans and return them to the wire rack; cool to room temperature, about 2 hours. Double‑wrap the cooled loaves in plastic wrap and store at room temperature up to 3 days, or wrap with an additional layer of aluminum foil and freeze up to 1 month.