Remove stems from strawberries. Using a paring knife, cut out centers; pipe Nutella into strawberries.
Insert a toothpick into the side of each strawberry. Holding toothpick, quickly dip stem end of strawberry into melted chocolate; allow excess to drip off. Sprinkle with hazelnuts; place strawberries on a waxed paper-lined baking sheet, point side up. Remove toothpicks; refrigerate strawberries until set. Just before serving, dust with confectioners' sugar.