In a small bowl, combine warm milk, active dry yeast, and 1 tablespoon of sugar. Stir gently and let sit for 5-10 minutes until the mixture is foamy.
In a large mixing bowl, whisk together the all-purpose flour, unsweetened cocoa powder, remaining sugar (3 tablespoons), and salt.
Add the melted butter, egg, and vanilla extract to the yeast mixture and stir to combine.
Pour the wet ingredients into the dry ingredients and mix until a dough forms.
Turn the dough onto a lightly floured surface and knead for about 8-10 minutes until smooth and elastic. If the dough is too sticky, add flour a tablespoon at a time.
Gently knead in the semisweet chocolate chips until evenly distributed throughout the dough.
Place the dough in a lightly greased bowl, cover with a clean kitchen towel or plastic wrap, and let it rise in a warm place for 1 to 1 1/2 hours or until doubled in size.
Preheat the oven to 350°F (175°C).
Punch down the risen dough and shape it into a loaf.
Place the shaped dough into a greased 9×5-inch loaf pan. Cover and let rise for another 30 minutes until it puffs up slightly.
Bake the bread in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean and the top is firm to the touch.
Remove the bread from the oven and let it cool in the pan for 10 minutes.
Transfer the bread to a wire rack to cool completely before slicing.