Preheat the oven to 350 degrees Fahrenheit.
Add the hazelnuts to a baking sheet and roast for 10 minutes.
Remove from the oven and wrap in a large dish towel. Use your hands to rub the hazelnuts around to remove the skins. They won't all come off and you'll need to manually remove some, but that's ok!
Add the skinned hazelnuts to a high speed blender or food processor and blend on high. Scrape down the sides as needed or use the tamper tool in your blender to press them down.
Once a butter starts to form (a few minutes in a high speed blender, about 8 in a food processor), add the chocolate chips to a microwave safe bowl and microwave at 30 second intervals until melted, stirring between each interval.
Meanwhile, add the cocoa powder and sugar to the blender and blend until smooth.
Add the melted chocolate, salt and vanilla to the blender/food processor and blend again until smooth and creamy. Taste and adjust flavors as desired, you can add more chocolate or more sugar to taste. If you want it sweeter without the added sugar, stevia works well! Then just continue to blend until completely smooth and creamy.
It will harden as it cools because the melted chocolate will firm up.
Transfer to a jar and store at room temperature for up to 2 weeks. It may firm up too much as it sits, so just microwave it for 20-30 seconds to soften it up as needed.