Toast the hazelnuts for 15 minutes at 350°F for 15 minutes
Immediately transfer the hot hazelnuts to a kitchen towel and then encasing them in the towel rub them to get the skins off. (Don't worry if you can't get them all off)
Transfer the nuts to a food processor and process to butter.
This will take 5-7 minutes, stopping to scrape the sides a couple times to make an even paste.
At this point you can add the optional sugar and if the paste seems too dry you can add the oil for a creamier spread
Recipe by Gretchen's Vegan Bakery at https://www.gretchensveganbakery.com/raspberry-linzer-mousse-cake/