Place prunes and hot coffee in a heat-proof bowl. Cover with a kitchen towel or a plate. Allow prunes to sit in coffee to re-hydrate, at least a couple of hours, overnight is best. It does not have to be refrigerated while re-hydrating.
Drain off and save any remaining coffee. Place drained prunes and vanilla extract into food processor. Pulse then process to puree prunes, adding reserved coffee (or water) one tablespoon at a time if the mixture is too thick to spin.
Remove lid of food processor, add cocoa powder and salt. Cover the feed tube of the food processor with your hand (so any loose cocoa powder doesn't come flying out). Pulse prune cocoa mixture until well combined, adding reserved coffee or water a teaspoon at a time to thin out consistency.
Transfer Chocolate Spread to container with air-tight lid. If serving on a Dessert Charcuterie Board, transfer to a small bowl.
Store leftover Chocolate Spread in air-tight container in the refirgerator for up to two weeks.