Mix cocoa powder and salt with flour in a large bowl until well dispersed.
Add in the rest of the ingredients and mix well for a few minutes. Let rest for 10 minutes.
Over a period of one hour, do 3 sets of stretch and folds, flipping the dough upside down after each set.
Cover the bowl with plastic wrap and place in the refrigerator overnight for about 10-12 hours.
Turn the dough on a lightly floured work surface. Divide into 3 equal parts and shape into rectangles. Let rest for 15 minutes.
Start preheating oven to 490F, with a 14 x 16 inch baking stone on the top rack and a bread pan filled with hot water on the bottom rack.
Divide the dough into 3 pieces and shape them into rectangles. Stretch each dough rectangle slightly and fold into a cylinder, sealing the seams. Using your hands, roll the cylinders gently stretching them to desired length, about 16 inches.
Place the cylinders on a floured surface, seam side up, side by side. Cover with a plastic wrap and prop from each side to ensure the baguettes hold their shape.
Proof at a room temperature for about 30 minutes.
Remove the plastic wrap, pull the baguettes apart. Turn them seam side up and brush off excess flour. Using a sharp knife or a razor blade, make 3-4 scores on each baguette. When scoring, use a swift and firm motion to ensure nice and clean cuts.
Open the oven, taking caution not to get burned by steam, and slide baguettes off onto the baking stone. Close the oven and reduce temperature to 480F.
Bake for 15 minutes.
Rotate, drop the temperature to 450F and continue baking for another 10-15 minutes, until deep brown.