Combine the Nutella and coconut oil in a small, microwave-safe bowl. Microwave for 30 seconds. Stir until combined.
If needed, microwave at 10 second intervals, stirring in between. The resulting sauce will be very smooth. Allow to cool slightly.
Then, simply pour over cold ice cream.
You can store this magic shell in an airtight container at room temperature. Should it harden based on the temperature in your house, just microwave the sauce for a few seconds until smooth.