01 - Preheat oven to 425°F. Line a large baking sheet with parchment paper.
02 - In a large bowl, toss Brussels sprouts with olive oil, garlic, salt, pepper, and red pepper flakes until evenly coated.
03 - Spread Brussels sprouts cut-side down in a single layer on the prepared baking sheet.
04 - Roast for 20–25 minutes, flipping once halfway through, until golden and crisp on the edges.
05 - Remove from oven. Immediately sprinkle with Parmesan cheese, lemon zest, and half the lemon juice. Toss gently on the tray to coat.
06 - Taste and add more lemon juice if desired. Transfer to a serving dish and garnish with fresh parsley.