1. 1. Prepare the Starter and Liquids: In a large mixing bowl, combine your active sourdough starter with the warm water. Whisk until the starter is mostly dissolved. Add the cocoa powder, instant espresso powder, and granulated sugar, whisking until well combined and no lumps remain. The mixture should be a smooth, dark brown liquid.

2. 2. Combine Dry Ingredients: Add the fine sea salt and bread flour to the wet ingredients. Mix everything together with a sturdy spoon or your hands until a shaggy dough forms. Make sure all the flour is hydrated. Cover the bowl with a damp cloth or plastic wrap and let it rest for 30 minutes (autolyse).

3. 3. Perform Stretch and Folds: After the rest, gently incorporate the chocolate chips into the dough. Then, begin your series of stretch and folds. Every 30-45 minutes for the next 2-3 hours, grab a portion of the dough from one side, stretch it upwards, and fold it over itself into the center. Rotate the bowl and repeat this 3-4 times until all sides have been stretched and folded. This builds strength in the dough.

4. 4. Bulk Fermentation: Once your stretch and folds are complete, cover the bowl and let the dough bulk ferment at room temperature (around 70-75 F / 21-24 C) for 4-6 hours, or until it has noticeably increased in volume (about 30-50%) and looks bubbly.

5. 5. Shape the Loaf: Gently turn the dough out onto a lightly floured surface. Shape it into a tight loaf or boule. If you’re using a loaf pan, shape it to fit the pan. If you’re baking in a Dutch oven, shape it into a round boule. Place the shaped dough into a floured banneton or a bowl lined with a floured kitchen towel, seam-side up.

6. 6. Final Proofing: Cover the banneton or bowl and let the dough proof at room temperature for 1-2 hours, or refrigerate for 8-12 hours for a deeper flavor development. The dough should feel puffy and slightly jiggly when gently poked.

7. 7. Bake the Loaf: Preheat your oven to 450 F (232 C) with a Dutch oven inside for at least 30 minutes. Carefully remove the hot Dutch oven, invert the dough into it, score the top with a sharp knife or lame, and bake covered for 20 minutes.

8. 8. Finish Baking: Remove the lid of the Dutch oven, reduce the oven temperature to 400 F (200 C), and continue baking for another 20-30 minutes, or until the crust is deeply golden brown and the internal temperature reaches 200-210 F (93-99 C). Let the loaf cool completely on a wire rack before slicing.