2 cups whole-wheat flour
2 cups all-purpose flour
1 teaspoon baking soda
1 teaspoon salt
2 1/4 cups buttermilk
Preheat oven to 450°F. Coat a baking sheet with cooking spray and sprinkle with a little flour
Mix whole-wheat flour, all-purpose flour, baking soda and salt in a large bowl. Make a circle in the center and pour in buttermilk. Stir in full circles until all the flour is incorporated. The dough should be soft but not too wet and sticky. When it all comes together (should only take a few seconds) turn it out onto a well-floured surface.
Pat and roll the dough to give it a round shape. Flip over and flatten slightly to about 2 inches. Transfer the loaf to the prepared baking sheet.
Bake the bread for 20 minutes. Reduce oven temperature to 400° and continue to bake until the loaf is brown on top 30 to 35 minutes more. Let cool for about 30 minutes.