Spoon the Nutella or hazelnut spread into a microwave-safe bowl. Heat the heavy whipping cream in a separate cup or bowl at high power for 45 seconds, or until very hot. Slowly whisk the cream into the bowl of Nutella, until very smooth. Allow to sit for an hour (it will thicken up).
Store in the fridge until ready to serve.
Before serving, on low setting, heat up the fondue in the microwave (or you can use stove top).
On a large prepared board, place the fondue under a hot pad, in the center of the board.