In the bowl of a stand mixer, combine the water, honey, oil, and salt.
Add the rye flour, 1 cup of the hard white wheat flour, and caraway seeds and combine. Let the dough rest for 15 minutes.
Add the yeast and remaining flour, if needed. Add a half cup at a time, watching to see when it starts to pull away from the sides of the bowl. Do not add anymore flour once it starts doing this.
Knead until you have a smooth dough and you reach windowpane. The dough should be smooth and just a little bit sticky.
Remove half of the dough from the bowl and set in a greased bowl. To the remaining half of dough in the mixer, add the cocoa powder and molasses. Mix until fully combined.
Place in a bowl and cover to rise. Let both doughs rise until doubled in size, about an hour.
Once risen, turn the dark rye dough out onto an oiled or lightly floured surface. Roll into a 13 x 9 inch rectangle. Set aside and roll the light rye dough into the same size rectangle. Place the darker dough on top of the lighter dough and roll up into a log. Pinch the ends together. Place into a greased 9 x 5 inch loaf pan seam side down.
Cover and allow to rise in a warm place until doubled in size, 40 minutes to an hour.
Preheat the oven to 350 degrees F. and bake for 30-35 minutes, until it reaches an internal temperature of 190 degrees F.