Preheat the oven to 400°F (200°C).
In a large bowl, combine the halved Brussels sprouts, olive oil, balsamic vinegar, maple syrup, garlic powder, salt, and pepper.
Spread the Brussels sprouts in a single layer on a baking sheet lined with parchment paper.
Roast in the oven for 25-30 minutes, stirring halfway through.
Optional: In the last 5 minutes of roasting, sprinkle chopped nuts over the Brussels sprouts.
Remove from the oven and toss with additional balsamic vinegar or maple syrup to taste, if desired.
Serve warm, garnished with additional chopped nuts, if desired.