In a food processor, puree the hazelnuts until they turn into nut butter, then add in the coconut oil, cocoa powder, coconut sugar, and salt. Puree until smooth.
Clean out the food processor, then puree the bananas until they reach a smooth ice cream like consistency. Transfer the banana mixture to a freezer-safe container and sprinkle with the hazelnuts and cacao nibs. Freeze until solid.
When ready to serve, scoop the ice cream into a bowl and top with the nutella sauce.