Pre-heat oven to 400℉
Soak brussel sprouts, massage in water, and rinse to clean. Drain completely and pa dry with paper towels. (The drier they are, the better they crisp in the oven)
Trim and half the Brussel sprouts and place them in a mixing bowl.
Toss brussel sprouts with olive oil, minced garlic, salt, pepper, and red pepper flakes.
On a sheet tray, line the Brussel sprouts cut side down in a single layer.
Bake for 20-25 minutes, flipping halfway through until golden brown and crispy on the edges.
Remove from oven and immediately toss in lemon juice, lemon zest, and grated parmesan cheese. Serve warm.