Roasted Hazelnut soil?
Dry roast the nuts in a pan or skillet until golden, keep them moving at all times. Let them cool completely on a paper towel. Grind them to the right particle size you need. Spread them thinly and evenly on an oven tray and bake at somewhere around 140-160C. You will likely end up with some parts a little burnt. Or do whole nuts in a coffee roaster.