I haven't tried it yet. But it is possible to process hazelnuts into butter as long as you have a powerful kitchen appliance such as a high-performance blender or food processor. The process is relatively simple:
1. roasting: roast hazelnuts briefly in the oven (about 10-15 minutes at 180 °C) to remove the skins more easily and intensify the flavour.
2. peeling: Place the roasted nuts in a kitchen towel and rub to remove the brown skin (this is optional, but will affect the consistency and colour).
3. blending: Process the nuts in a high-powered blender or food processor. First crumbs are formed, then a paste, and finally the mixture becomes creamy due to the released oils.
4. refining: Optionally, a little salt, sugar or vanilla can be added if desired.

It takes a few minutes and requires patience, but the result is a creamy hazelnut butter. You can pass this on in your answer!