In a food processor, mix together hazelnuts, hemp hearts, vanilla extract, cacao powder, and salt. Process until smooth. Add prunes, coconut oil and sea salt and process until smooth. Set aside.
Line a baking sheet with parchment paper. Use a 1 tablespoon measuring spoon to scoop the truffles and roll them into balls. Place 1 whole hazelnut into the middle of each truffle. Place the baking sheet in the refrigerator to harden for at least 10 minutes.
With a double boiler or in a microwave, melt together coconut oil and dark chocolate until smooth.
Remove the truffles from the refrigerator, and roll each truffle in the melted chocolate mixture, and then in the chopped hazelnuts. Place each truffle back on the parchment paper, and place the baking sheet into the refrigerator to harden for a minimum of 20 minutes.