Spray a 9x5-inch loaf pan with nonstick cooking spray. Set aside.

To a large bowl, add all-purpose flour, bread flour, rye flour, cocoa powder, yeast, sugar, and salt. Whisk to combine.

In the bowl of a stand mixer fitted with a dough hook attachment, mix together the warm water, molasses, and vegetable oil.

Gradually add the dry ingredients to the wet ingredients. Mix on low speed until a dough forms, 1-2 minutes.

Knead for 5-8 minutes, until the dough is smooth and elastic. Alternatively, you can turn the dough out onto a lightly floured surface and hand knead for about 8-10 minutes.

Place the dough in a large, clean, oiled bowl and cover. Let it rise in a warm place until doubled in size, about 60-90 minutes.

Once the dough has risen, roll it out onto a lightly floured work surface. Flatten the dough into a rectangle, roughly the width of the loaf pan.

Starting at the short end, roll the dough tightly to form a log, pinching the seams as you go to create a tight surface.

Place the rolled dough seam-side down into the prepared pan.

Cover and let the dough rise in a warm place until it has doubled in size, about 45 minutes.

Preheat oven to 375°F (190°C) as the dough completes its second rise.

Bake the loaves for about 50-55 minutes, or until the bread sounds hollow when tapped.

Remove the bread from the oven. Let it cool completely on a wire rack before slicing.

Store the bread at room temperature for up to 3 days or freeze for up to 8 weeks.