Preheat the oven to 400℉ and lightly crease a light colored baking pan (cake pan, oven safe skillet, or shallow casserole).
In a large bowl whisk together the whole wheat, White Lily all-purpose flour, wheat bran, brown sugar, baking powder, baking soda, and salt so that everything is combined and evenly distributed.
2 cups whole wheat flour, 2⅓ cups White Lily all-purpose flour, ¼ cup wheat bran, 3 tablespoons brown sugar, 2 teaspoons baking powder, 1 teaspoon baking soda, 1 teaspoon salt
Make a well in the center of the dry ingredients and pour the buttermilk, then the melted butter into the well.
1½ cups Buttermilk, 3 tablespoons butter
Using a spatula, quickly combine all the ingredients. There will be some lumps and flour still visible. Turn out onto a parchment paper surface (or lightly floured surface) and using your hands pull the dough together. Knead about 10 to 12 times, shaping into a ball while doing so.
Place the ball of dough into the prepared baking pan. Press down lightly so that the ball flattens a little. This will help prevent a doughy center and a more evenly baked loaf.
Brush the ball of dough with some additional buttermilk and sprinkle on the rolled oats.
Buttermilk, rolled oats
Bake in the preheated oven for 60 minutes. Check the center with an instant read thermometer and continue baking in 5 to 10 minute intervals until it reaches 200℉ (93.3℃).NOTE: The baking time can vary from 60 minutes to as much as 1 hour 15 minutes due to differences in ovens and baking conditions. Remove the pan of bread from the oven and allow to cool for 10 minutes, then transfer to a cooling rack. Allow to cool until comfortable to handle before slicing. Serve warm or cold.