In a preferably small food processor or other mixer process the hazelnut butter, melted chocolate, salt, dates, and milk smooth.
On a plate or cookie tray lined with plastic wrap or parchment paper place out half of the banana slices. Divide the nutella between the slices, top with some chopped hazelnuts, put another banana slice on top, and freeze for at least three hours or until frozen. Before serving optionally dust/sprinkle some cocoa powder on top of the bites. Enjoy!