Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease it.

Prepare Brussels sprouts: Trim the stems and remove any yellow outer leaves. Cut larger sprouts in half, keeping smaller ones whole for even cooking.

In a large bowl, toss Brussels sprouts with olive oil, minced garlic, salt, and black pepper until evenly coated.

Spread sprouts in a single layer on the prepared baking sheet. Roast for 20-25 minutes, stirring halfway, until crispy and golden brown.

Remove from oven and immediately drizzle with lemon juice. Sprinkle with parmesan cheese and red pepper flakes (if using). Toss gently to combine.

Transfer to a serving dish and garnish with extra parmesan if desired. Serve warm.