01 - Preheat oven to 425°F and line a large baking sheet with parchment paper.
02 - Toss Brussels sprouts and red onion with olive oil, salt, and pepper in a large bowl until evenly coated.
03 - Spread the vegetable mixture in a single layer on the prepared baking sheet.
04 - Roast for 20 minutes, stirring halfway through, until Brussels sprouts are golden and crisp on the edges.
05 - Remove from oven, sprinkle dried cranberries over the sprouts, and toss gently to combine.
06 - Roast an additional 3 to 5 minutes until cranberries are slightly softened.
07 - Transfer to a serving platter, drizzle with balsamic glaze, and sprinkle with toasted nuts if desired. Serve warm.