Grease 2 loaf pans with butter; coat bottoms and sides with 1 tablespoon cornmeal.
Mix 1 1/2 cup bread flour, 1 1/2 cup white whole-wheat flour, yeast, and baking soda together in a large bowl.
Combine milk, water, sugar, and salt in a saucepan over low heat; heat until mixture registers 125 degrees F (52 degrees C) on a thermometer, about 5 minutes.
Stir warm milk mixture into the flour mixture; add remaining 1 1/2 cup bread flour and 1 1/2 cup white whole-wheat flour. Mix until dough comes together.
Divide dough in half; place 1 piece in each loaf pan. Sprinkle remaining cornmeal on top. Cover and let rise in a warm place until doubled in size, about 1 hour.
Preheat oven to 400 degrees F (200 degrees C).
Bake loaves in the preheated oven until golden brown, 20 to 25 minutes. Invert onto a wire rack and cool to room temperature, about 30 minutes.
