Proof yeast in lukewarm water directly in the mixing bowl. Activate the mixer briefly to combine. Set aside for 5-10 minutes to allow the yeast to bloom. 

Melt butter in a saucepan. Shake or stir the buttermilk and pour it into the saucepan; stir. Test temperature with a finger, it should just feel warm, if you use a thermometer, 110 degrees. Add to the mixing bowl with the honey. 

Add the splash ring; turn the mixer on low speed, 1. Add whole wheat flour 2 cups at a time, then the baking soda and salt. Once it is nicely incorporated, add the white flour a cup at a time until you have a soft dough that pulls away from the sides of the bowl. Hold back some of the flour, you may not need it all!

Cover the bowl with lid. Let rest for 5 – 10 minutes. This gives the bran in the whole wheat flour time to hydrate which softens the edges making the dough easy to handle.

Set the mixer on low speed let it knead for 5 minutes. Touch the dough. It should feel smooth and resilient. Bread dough made with whole grain flour will retain a certain amount of stickiness, like the sticky side of a Post It note. This is okay and does not need to be eliminated. 

When you think you are done kneading, let the dough rest 5 minutes and then perform the windowpane test. Use clean scissors to cut off a walnut-size piece of dough. Slowly pull and stretch the dough to see if it will hold a thin membrane. Hold it up to a window; if you can see light through it, you are done kneading; if not, knead another minute or two, rest 5 minutes, and re-check.

Give the dough a few turns by hand on a lightly greased counter and shape it into a smooth ball. You will need an extra-large mixing bowl because this amount of dough will climb out of the Bosch bowl. If you have a scale, weigh the bowl and mark the weight on a piece of tape on the bowl. Grease it well and place dough in the bowl, smooth side up. Now weigh the bowl again. Subtract the first number, the weight of the bowl, from the second, to determine the actual weight of the dough. Cover with a clean cotton towel. Allow it to rise in a protected spot until almost doubled, 1 hour. Meanwhile, grease 5 loaf pans and set aside.

To check if it’s done rising, do the poke test: take 2 fingers and gently press the dough. When you withdraw them, the indentation should remain, but the dough should not “sigh” or deflate.

Turn the dough onto the work surface and gently but firmly flatten the entire surface with oiled palms to remove large air bubbles. Use a bench knife or a chef’s knife to divide the dough into 5 equal portions. This is where your scale comes in handy. By weighing the portions, you will have an easier time making even-sized loaves. If you don’t have a scale, that’s fine. You can eyeball it. 

Shaping: pat a piece of dough into an 8×12-inch rectangle. Roll it up from one narrow side. Pinch bottom seam to seal. Place seam side down in prepared loaf pan. 

Cover the bread pans and let rise until dough curves nicely over the top of the pan, about 35-45 minutes. Most ovens will fit 3 to 4 loaves at one time. Cover the extra loaves with oiled plastic wrap and set them in the fridge to slowly rise and wait their turn in the oven. Set the oven to 350°F (175°C) to preheat. The touch test will help you determine if your bread is ready to bake. Instead of poking your fingers into the dough, this time simply touch the dough. It should barely show your fingerprint.

Bake 35-40 minutes, until each loaf is well-browned and done. To test for doneness, carefully tip the loaf out of the pan and inspect the bottom. The crust should be evenly browned and sound hollow when thumped with a finger. A food thermometer will read 195-200°F (90-93°C). You will want to check each loaf individually to be sure it is baked completely. And if your oven heat doesn’t circulate properly, you may need to rotate the loaves on the rack about 15 minutes before the end of baking time.Cool baked loaf on a wire rack for a crisp crust or on a wooden breadboard for a softer crust. If desired, brush warm loaf with melted butter. Wait at least an hour before slicing to allow the crumb to set.