Prep Starter. The night before, feed your sourdough starter so you have 100 grams of active and bubbly starter the next day. (my favorite combination is 40 grams of unbleached all-purpose flour, 30 grams of filtered water, and 30 grams of sourdough starter)
Autolyze. In a large bowl add the sourdough starter and water. Stir to combine. Next, add the all-purpose flour, stir to combine, and allow the mixture to sit for 10 minutes.
Mix the remaining dry ingredients separately. In a small bowl add the whole wheat flour, salt, sugar, vanilla bean powder, and cocoa powder. Stir until fully combined.
Add dry ingredients to the dough. Add the cocoa powder mixture to the flour/water/sourdough mixture. Using a spatula try to incorporate everything together. Once it gets too hard to use the spatula, turn the mixture out onto a clean dry surface. Knead the dough so everything has been incorporated.
Rest. Cover the bowl and allow it to sit covered for 30 minutes.
Stretch and fold. Next start the stretch and folds. Wet your hands with warm water, pick up one side of the dough, stretch, and fold the dough over. Repeat this process 3 or 4 times. Flip the dough over. Cover the dough and allow it to sit for 30 minutes. Repeat the stretch and fold 2 more times. *This dough is a dryer dough so it may not stretch out too far and that is okay. The stretch and folds help strengthen the dough.*
First rise (Bulk Fermentatiion). After the last stretch and fold session, cover the dough and allow the dough to sit at room temperature for 6-8 hours or until the dough has doubled in size.
Add chocolate chips. Turn the dough out onto a clean dry surface.Fold the chocolate chips into the dough by adding about a 3rd of the chocolate chips, gently fold the dough, add another third, gently fold the dough, and add the last bit of chocolate chips, and gently fold the dough. **Try to avoid pressing too hard when folding so you don’t remove all of the air inside the dough.
Second rise. Shape the dough into a round shape so it fits nicely in your banneton. Transfer the dough to a well-floured banneton and cover with plastic. Place it in the fridge for 10-12 hours (overnight is best)
Preheat oven. Preheat the Dutch oven to 425 degrees F for a minimum of 30 minutes. (This helps make sure that the Dutch oven is at temperature)
Prep loaf. Take the dough out of the fridge and turn the dough out onto a piece of parchment paper or a silicone bread mat.Using a bread razor, score the dough down the center, shift the dough 90 degrees and score the dough again making a + sign or an X.
Bake, removing the lid partway. Transfer the dough to the hot Dutch oven. Cover and bake at 425 degrees F for 20 minutes. Remove the lid and reduce the heat of the oven to 375 degrees F. Bake for another 20 minutes.
Cool and Slice. Remove the bread from the oven and transfer it to a wire cooling rack. Allow the bread to cool completely (at least 1 hour) before cutting into it.