In a medium saucepan over medium heat, melt the 100 grams of chocolate and coconut oil.
100 grams semi-sweet chocolate, 1 1/2 tablespoons (20 grams) coconut oil
Take off of the heat and add the chopped hazelnuts and Nutella. Place in the freezer for about 20 minutes or until firm enough to roll into balls.
100 grams chopped and roasted hazelnuts, 100 grams Nutella
Roll into 1" balls (or whatever size you like), add a hazelnut on top, press down and place back into the freezer for a few minutes to harden a little again.
14 - 18 hazelnuts
Meanwhile, melt the remaining 120 grams of chocolate in a small saucepan over low heat, stirring occasionally to prevent burning.
120 grams semi-sweet chocolate chocolate
When melted, take the pan with the chocolate off the heat, take the chocolate balls out of the freezer, and dip in the melted chocolate. Place the coated balls on a Silpat or cooling rack to harden, about 1 hour. Store at room temperature for up to a week.