Step 1: Prepare the Hazelnuts. Preheat your oven to 350°F (175°C). Spread hazelnuts on a baking sheet and roast for 10-12 minutes.
Step 2: Blend the Ingredients. In a food processor, combine one cup roasted hazelnuts, cocoa powder, sugar, salt, and vanilla extract. Pulse until smooth.
Step 3: Form the Chocolate Balls. Take a small amount of the mixture and form into a ball, placing a whole hazelnut in the center.
Step 4: Chill the Balls. Place the balls on a baking sheet lined with wax paper and refrigerate for about 30 minutes.
Step 5: Coat with Chocolate (Optional). Melt chocolate chips and dip each ball, then roll in chopped hazelnuts if desired.
Step 6: Set and Serve. Return to wax paper and let set in the refrigerator for 15 minutes before serving.