In a food processor fitted with an "S" blade, process the hazelnuts into a fine powder. Add in the dates, cocoa powder, vanilla, and coconut oil and salt, and process again until a uniform texture is achieved. (You may need to stop and scrape down the bowl a couple of times!) Feel free to taste the batter at this point, and adjust any flavors to your taste.
Transfer the mixture to a baking sheet lined with parchment paper, and use your hands to press it into a rectangle about 1/2-inch thick. Place in the freezer to set for at least 1 hour before cutting and serving.
Store and serve directly from the fridge or freezer for best shelf life and texture.
Notes
If your dates aren't soft, soak them in warm water for 15 minutes beforehand.