1. Activate Your Starter and Combine Wet Ingredients: In a large mixing bowl, combine your active sourdough starter with the warm water. Stir gently until the starter is mostly dissolved. Add the granulated sugar, unsweetened cocoa powder, and instant espresso powder (if using) to this mixture. Whisk until everything is well combined and the cocoa powder is fully incorporated, ensuring no lumps remain. The mixture should be a smooth, dark brown liquid.

2. Add Dry Ingredients and Form the Dough: Gradually add the salt and 3 1/2 cups of all-purpose flour to the wet mixture. Use a sturdy spatula or your hands to mix until a shaggy dough forms. At this stage, it will look a bit rough and sticky, but all the flour should be hydrated. Avoid overmixing.

3. Incorporate Chocolate Chips and Knead Lightly: Turn the dough out onto a lightly floured surface. Gently knead for about 5-7 minutes, just until the dough starts to become smoother and more cohesive. It doesn’t need to be perfectly smooth like a traditional bread dough. Now, flatten the dough slightly and sprinkle the chocolate chips over it. Fold the dough over itself a few times to incorporate the chocolate chips evenly. Be careful not to overwork the dough once the chips are in.

4. First Rise (Bulk Fermentation): Lightly grease a clean large bowl with a tablespoon of melted butter. Place the dough in the bowl, turning it once to coat all sides with butter. Cover the bowl with plastic wrap or a clean kitchen towel. Let the dough rise in a warm spot for 2-4 hours, or until it has visibly increased in size by about 50-75%. It won’t necessarily double like a yeast dough, but it should look puffy and feel airy.

5. Shape the Loaf and Prepare for Baking: Gently turn the dough out onto a lightly floured surface. Shape it into a round or oval loaf, being careful not to deflate it too much. You can gently tuck the edges under to create surface tension. Place the shaped loaf onto a baking sheet lined with parchment paper. If you have a Dutch oven, you can also place it directly into a parchment-lined Dutch oven for baking.

6. Bake the Chocolate Sourdough: Preheat your oven to 425 F (220 C) with a Dutch oven inside, if using, for at least 30 minutes. If not using a Dutch oven, simply preheat the oven. Once preheated, brush the top of the loaf with the remaining melted butter. If desired, you can sprinkle a little extra sugar on top for a sweet crust. Bake for 35-40 minutes, or until the crust is golden brown and the internal temperature reaches 200-210 F (93-99 C). If baking in a Dutch oven, bake covered for the first 20 minutes, then uncover and bake for another 15-20 minutes.

7. Cool Before Slicing: Once baked, remove the bread from the oven and transfer it to a wire rack to cool completely. This is a crucial step for the internal texture to set properly. Slicing too early can result in a gummy texture. Wait at least 1-2 hours before cutting into your delicious chocolate sourdough bread.