Instructions

• Measure the lukewarm water (105 to 115°F). In a small bowl, sprinkle the yeast over 1/4 cup of the water and let stand until foamy, about 5 minutes.
• In a food processor fitted with the dough blade, combine the all-purpose flour, whole wheat flour, and salt. Pulse briefly to mix.
• With the machine running, pour the yeast mixture and the remaining 1/2 cup water through the feed tube until the dough just forms a ball. Continue to knead the dough by pulsing until it is smooth and no longer sticky, about 30 pulses.
• Spray a large bowl with nonstick cooking spray. Transfer the dough to the bowl, cover loosely with a clean dish towel, and let rise in a warm, draft-free place until doubled in volume, about 1 hour.
• Punch down the dough. Lightly sprinkle a work surface with the extra all-purpose flour and turn the dough out onto the surface. Roll the dough into a 12 x 16-inch rectangle.
• Fold the rectangle into thirds lengthwise (like a letter), pinch the seams to seal, and shape the dough into a 12-inch tapered oval loaf.
• Spray a baking sheet with nonstick cooking spray. Sprinkle 1 teaspoon cornmeal in a 12-inch strip down the center of the sheet. Place the loaf on the baking sheet on top of the cornmeal. Cover loosely with plastic wrap or a damp towel and let rise in a warm, draft-free place until doubled in volume, about 30 minutes.
• Spray the top of the risen loaf lightly with nonstick cooking spray. Evenly sprinkle the top with the finely chopped fresh rosemary and the flaky sea salt. With a serrated knife, make 2 to 3 slashes across the top of the loaf.
• Place the baking sheet with the loaf in the upper third of a cold oven. Set the oven to 400°F and bake about 20 minutes.
• After 20 minutes, reduce the oven temperature to 350°F and continue baking 20 to 25 minutes longer, until the loaf sounds hollow when tapped on the bottom.
• Remove the loaf from the baking sheet and cool completely on a rack before slicing.