Place the dates in a medium bowl. Pour enough warm water on top to submerge them completely. Let soak for about 15 minutes, until the dates have softened.

Remove the dates from the water and place them in a food processor. Add the cocoa powder, coconut oil, vanilla extract, and salt. Blend until a smooth and sticky paste forms, about 1 minute. Scrape down the sides and bottom with a spatula and blend for another few seconds. Add the dark chocolate pieces and pulse until evenly distributed throughout the paste.

Transfer the mixture to a clean bowl. Refrigerate uncovered for about 20 minutes.

Using a 1-tablespoon cookie scooper, scoop out the paste and release onto a half-size baking sheet lined with a piece of parchment paper. Continue with the remaining paste, leaving about two inches of space in between each mound.

Transfer the baking sheet to the refrigerator and chill for about 20 minutes, until slightly firm.

Place the cocoa powder and chopped nuts in two separate shallow bowls. Remove the baking sheet from the refrigerator.

Roll one mound in the palms of your hands to create a ball, then roll it in the cocoa powder or chopped nuts to completely coat the exterior. Place in a mini cupcake liner and set on a large serving plate or platter. Continue with the remaining mounds, rolling half of them in the cocoa powder and half in the chopped nuts.

Transfer the platter to the refrigerator and chill for about 1 hour before serving.

Store the truffles in an airtight container in the refrigerator for up to 1 week.