Place one oven rack in the upper third of the oven and another in the lower third of the oven. Put two baking trays inside to heat them up. Heat the oven to 425°F.
Place the cleaned and trimmed sprouts in a microwave-safe dish with ¼ cup water. Cover with a damp paper towel and microwave for 7–10 minutes until fork tender. Alternatively, steam them in a pot with a steamer basket and about 1 inch of water until just tender.
1½ lbs medium sized Brussels sprouts
Drain the steamed Brussels sprouts in a colander in the sink and rinse with cold water to stop the cooking process. Transfer the sprouts to a clean dish towel and dry thoroughly.
Once dry, transfer to a large bowl. Toss in olive oil, salt, pepper, garlic powder, and nutritional yeast.
2 TBS olive oil, ¼ cup nutritional yeast, 1 tsp garlic powder, 1 tsp salt, ½ tsp pepper
Carefully remove hot trays from the oven. Spread the Brussels sprouts evenly across both trays. Smash each sprout to about ½-inch thickness with the bottom of a glass or measuring cup. If needed, use a rubber spatula to scrape the seasonings from the bottom of the cup and spread them carefully back onto the Brussels sprouts.
Place trays back in the oven. Bake for 10 minutes, then switch the trays (top to bottom, front to back). Bake another 10 minutes until golden brown and crispy on the edges.
Let Brussels sprouts cool on the tray, then transfer to a platter. Serve at room temperature as a side dish or appetizer with a dip on the side.