Preheat oven to 350 and line baking sheet with parchment paper.
Spread hazelnuts evenly on baking sheet and roast for 15 minutes until golden brown and fragrant.
Transfer hazelnuts to high-speed blender, increasing speed until hazelnuts are very finely chopped (~3 minutes).
Once chopped, use the tamper to continue to blend until the mixture starts to form a "butter" consistency.
Add the cocoa or cacao and vanilla extract and continue to blend on medium until desired consistency.
Transfer to a mason jar and allow mixture to return to room temperature before storing.