In a preserving pan, mix the cherries with the sugar and lemon juice. Bring to the boil and cook 5 minutes, stirring gently and skimming carefully. Add the chocolate and stir until it melts. Pour into a ceramic bowl and cover with a sheet of parchment paper and refrigerate overnight.
The next day, return the mixture into a preserving pan. Continue cooking on high heat for about 5 minutes, constantly stirring. Return to a boil. Put the jam into sterilized jars immediately and seal.
Recipe by the modern barista at https://themodernbarista.com/index.php/2016/04/25/ethiopia-mocca-java-chocolate-cherry-jam/