Prepare the Dough: In a large bowl, whisk together the flour, cocoa powder, sugar, yeast, and salt. In another bowl, combine the warm milk, eggs, melted butter, and vanilla extract. Gradually add the wet ingredients to the dry mixture, stirring until a sticky dough forms. If using, fold in the chocolate chips or nuts.

Knead and Rise: Transfer the dough to a floured surface and knead for 8–10 minutes until smooth and elastic. Place the dough in a greased bowl, cover with a damp cloth, and let it rise in a warm spot until doubled in size, about 1–2 hours.

Shape and Second Rise: Punch down the risen dough to release air bubbles. Shape it into a loaf and place it into a greased loaf pan. Cover and let it rise again for 30–45 minutes until puffed.

Bake: Preheat the oven to 350°F (175°C). Bake the bread for 30–35 minutes. To check for doneness, insert a toothpick into the center; it should come out clean or with a few crumbs. Allow the bread to cool before slicing.