Step 1

Adjust oven rack to middle position and heat oven to 375 degrees. Lightly grease 8-inch round cake pan. Whisk whole-wheat flour, all-purpose flour, wheat bran, wheat germ, sugar, baking powder, baking soda, and salt together in medium bowl.

Step 2

Add buttermilk and stir with rubber spatula until all flour is moistened and dough forms soft, ragged mass. Transfer dough to counter and gently shape into 6-inch round (surface will be craggy). Using serrated knife, cut ½-inch-deep cross about 5 inches long on top of loaf. Transfer to prepared pan. Bake until loaf is lightly browned and center registers 185 degrees, 40 to 45 minutes, rotating pan halfway through baking.

Step 3

Invert loaf onto wire rack. Reinvert loaf and let cool for at least 1 hour. Slice and serve.