Add 1/2 pint jars to canner and get water bath canner heated up.
Add sugar, cocoa powder, water and salt to a large stockpot. On medium heat, whisk and heat until all sugars are dissolved. It will be glossy. No need to boil here.
Remove from heat.
Remove 1/2 pints from canner. Dump out water and fill with chocolate concentrate to about 1/2” headspace. Wipe rims with a vinegar rag.
Place lids and rings on fingertip tight.
Add to canner and add canning lid. Lower and once it hits a rolling boil, can for 15 minutes.
Once 15 minutes is up, shut off heat and remove the lid. I leave for about 15 minutes. Then raise the canning grate up and let sit another 10 minutes or so. You should hear the lids start to pop and seal. Hooray!
Remove and set on a towel for a day then store in a cool dark place for up to a year or two. Or longer if preferred.
