Knead all whole wheat and rye flour, buttermilk, flaxseed, yeast, butter and salt in a bowl until well combined. Knead for about 3 minutes on the highest speed.
Then cover the bowl and let the dough rise for about 1/2 hour. Then knead briefly and place in loaf pan, cover again and let rise for another 30-45 minutes.
Preheat the oven to 180 °C hot air and bake for about 45 minutes. After baking, remove from the mold and let cool well.
Preparation Tip:
The dough can be varied with caraway seeds, sunflower seeds, onions, wheat germ or wheat bran to taste.