First toast the hazelnuts at 160 °C for 20 minutes.
Meanwhile cut the celeriac into big cubes and blanch them in some salted water till cooked.
Once you take them out of the water don't cool them down but transfer them directly into a blender.
Also add the toasted hazelnuts and the remaining ingredients and blend this till smooth. This is going to take a couple of minutes, but it really needs to be smooth.
Then spread it on a silicon sheet using a stencil and bake them at 110 °C for 2 hours. After that remove them one by one from the stencil and directly press them between the wood press. I always heat up the press a bit, this prevents the crisp from breaking.
Now keep them dry and covered to prevent them from turning soft.
