Preheat oven to 350 degrees F. Bake hazelnuts for 10-12 minutes until toasted and skins begin to separate from hazelnut. Rub the warm hazelnuts in a clean dish towel to remove the skins. Let hazelnuts cool to room temperature.
Place cooled hazelnuts in a jar or bowl. Pour in enough cool water to submerge the nuts. Cover and let sit for at least one hour, up to 24 hours.
Drain and rinse the hazelnuts. Place in blender. Add filtered water, pitted dates, and cacao powder. Blend at the highest speed for 45 seconds to 1 minute until the nuts have been ground.
Separate liquid mixture using a nut bag, or cheese cloth set over a mesh strainer. Discard hazelnut pulp, or save to add to smoothies, baked goods, or pancake batter.*
Pour cacao hazelnut milk into an airtight container and keep chilled in the fridge for up to three days. Shake well before servings. Mixture will separate as it sits.