Prep brussel sprouts by trimming the ends, removing outer leaves and slicing in half. Put prepped brussel sprouts in a large bowl. Drizzle with olive oil and season generously with salt and pepper. Stir in smashed garlic.
Spread brussel sprout mixture evenly on a large baking sheet. Roast in oven for 10 minutes. Top with parmesan cheese and roast for another 10 minutes. Serve warm and enjoy!