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