This is a recipe adaptation from bakersandbest.com
100g. levain 100% hydration
400g. filtered water
450g bread flour
50g wholemeal flour
40g. cacao powder
125g (max) additions of which I have tried cramdberries, cherries and nuts mix, dates and nuts, chocolate chunks, cacao nibs, or just a mix of seeds and/or nuts.
extras: some semolina or rice flour, extra flour for dusting, proofing vessel or loaf tin, dutch oven or covered roaster that is big enough to hold your final loaf ie bigger than your tin or banetton with enough headroom for the rise when baking.
Prepare your levain by mixing up to 10g of your starter with 50g each of flour and filtered water. leave to rise overnight. Test your levain next day by dropping a small spoonfull in a cup of water, if it floats it is ready to use.
Mix 375g of the water with the levain, add the floours and cacao, mix into a shaggy mass ensuring all the dry ingredients are hydrated, specially at the bottom of the bowl.
leave this to rest, cvered 30 min. to an hour.
Add the salt to the rest of the water (25g), mix into the dough. Ensure this is well incorporated. Cover and leave to rise for 30 minutes.
Mix in your additionals at this point, incorparating by way of stretching and folding. My method is to flatten out the dough on a lightly floured surface, lay the additional ingredient on top then fold into 3 envelope style. Turn then repeat 2-4 times then put onto the bowl or box, cover and let rise for at least 2 hours with 2-3 more stretch and folds. this helps with the gluten development.
At the last stretch and fold, leave to rise for an hour, covered.
remove from the bowl/box onto a lightly floured surface. fold in from the top and sides to a rough round shape. Turn this over so the seams are underneath. Pull the dough with the edges of your palms towards you to tighten the skin a few times. let it rest 30 minutes covered by un upturned bowl. Meanwhile prepare your proofing vessel ( banneton or loaf tin)
Sprinkle some flour on the surface of your dough ball then gently flip over with the help of a dough scraper if possible so that the floured top is now on your work surface. Shape it to fit you basket or loaf tin. Place seam side down in a tin, seam side up in a banneton. Place in a plastic bag that can be loosely tied, a lidded plastic box, or use a disposable shower cap. WHatever you use, it needs to be bigger than the proofing vessel to give the dough space to rise. Let rest for an hour on the kitchen bench then place in the fridge to proof overnight (8 hours at least in 4c temp). Or you can proof at room temp for 3-4 hours then bake.
When ready to bake, remove from the fridge an of hour beforehand. Then preheat your oven with your dutch oven or covered roaster in it, for at least an hour to 250C or as hot as it will go. When it is to temp., turn your dough out from the banneton onto a peel or a a cookie sheet with or with out nonstick paper but dusted with rice flour or semolina. Score the loaf, which is now the right side up, with a lame, a very sharp knife or blade. If baking in a loaf tin, score the top of the loaf. Place it carefully in the pre-heated dutch ove or roaster, then place the lid on. Turn the oven down slightly to 220C
Bake with the lid on for 20 minutes, remove lid and bake a further 20-25 minutes. Switch the oven off but leave the loaf in a further 10 minutes with the door slightly ajar.
Turn out onto a wire rack and leave to cool completely before slicing.
It will be tempting but it is best to wait till it is completely cool. The dough is still cooking inside.