Roast the hazelnuts in a preheated oven at 200 °C for 8-10 minutes, until the hazelnuts glisten with oil. Cool them down until they are just warm to the touch. Take them in a grinder jar and grind, scraping down the sides of the jar at intervals, until you obtain a smooth butter.
Add the dates and cacao powder and grind it into a smooth paste while scraping the sides down. Do not add water.
Store in an airtight jar.