Preheat oven to 425 F.
Line a baking sheet pan with parchment paper.
In a large bowl, add ice cold water and set aside.
Fill a large pot with water and a generous few pinches of salt. Place it over high heat on the stove, letting it come to a boil. Once boiling, add in the brussels sprouts and cook for about 10 minutes, until you can easily stick a fork in them.
Remove these from the heat, drain the water and place brussels sprouts into the ice water. Let them sit in the cold water for 30 seconds, then drain.
Spread the brussels sprouts onto the baking sheet. Use the back of a cup to press them down to flatten.
In a small bowl, mix the oil and garlic then use a pastry brush to drizzle and spread the garlic mixture over top.
Add the parmesan ingredients to a spice grinder. Grind the mixture until there are tiny cashew chunks remaining. Do not grind it to a fine powder.
Spread the parmesan mixture evenly over the brussels sprouts, tossing to coat both top and bottom with the parmesan.
Place the baking tray in the oven for 15 minutes, turning the tray around halfway through to allow the parmesan to evenly bake.
Once done, remove from the oven. Add the brussels sprouts to a serving dish and sprinkle with fresh herbs. Enjoy!