Whisk flours, cocoa powder, yeast, sugar, and salt in a large bowl.

Gradually add warm water, molasses, and oil. Mix until a shaggy dough forms.

Knead for 5–8 min with a dough hook or 10 min by hand until smooth and elastic.

Place dough in a greased bowl, cover, and let rise in a warm place for 60–90 min.

Punch down, shape into a log, and place in a greased 9x5-inch loaf pan.

Cover and let rise again for about 90 min until puffy.

Preheat oven to 375°F (190°C). Bake for 35–40 min until loaf sounds hollow when tapped.

Cool completely on a wire rack before slicing.