Preheat your oven to 400°F (200°C).
In a large bowl, combine the halved Brussels sprouts, olive oil, garlic powder, salt, and black pepper. Toss until the Brussels sprouts are evenly coated.
Spread the Brussels sprouts in a single layer on a baking sheet lined with parchment paper.
Roast in the preheated oven for 20-25 minutes, stirring halfway through, until they are golden brown and crispy on the edges.
Remove from the oven and sprinkle the grated Parmesan cheese over the Brussels sprouts. Return to the oven for an additional 5 minutes, or until the cheese is melted and bubbly.
Drizzle with balsamic vinegar if desired before serving.