Add hazelnuts to a high speed blender or processor and blend on high speed for 5-8 minutes. Scrape down the sides every minute until you reach a smooth consistency, like a nut butter
Melt chocolate chips and oil in a microwave safe bowl in 30 second increments, until you have a smooth consistency
Add the melted chocolate to the hazelnut butter and blend
Transfer to a container and place in the fridge for 1-2 hours until it solidifies