Process the dates and ½ cup of hazelnuts (reserve the remaining ½ cup) in a food processor or high speed blender for about 2 minutes.
Add the reserved hazelnuts, cacao butter, cacao powder, vanilla, salt and maple syrup to the food processor and process for 1 minute.
Line a cookie sheet or large plate with parchment paper. Roll the mixture into small balls, using about 2 teaspoons of the mixture per ball (I use this cookie scoop). Set each ball on the parchment paper and refrigerate until you melt the chocolate.
Melt the chocolate slowly in a double boiler or microwave. Cut a small hole in one end of a plastic bag and fill the bag with the melted chocolate. Drizzle melted chocolate over the balls and serve. Store in an airtight container in the fridge or at room temperature.
I used blanched hazelnuts in this recipe and below is a link to the one I usually buy already skinned. You can use hazelnuts with the skin on in this recipe, but the texture might not be as smooth. If you like, you can remove the skins from your hazelnuts easily and I have a tutorial on how to do this here.