Preheat the oven. Preheat the oven to 425°F (220°C). Line a large baking sheet with parchment paper if desired.
Prepare the Brussels sprouts. Trim the woody ends from the Brussels sprouts and remove any damaged outer leaves. Cut the sprouts in half and pat them thoroughly dry.
Season the sprouts. Place the Brussels sprouts in a large bowl. Add the olive oil, salt, black pepper, and garlic powder if using. Toss until the sprouts are evenly coated.
Arrange on the baking sheet. Spread the Brussels sprouts in a single layer on the baking sheet. Place as many of the sprouts as possible cut-side down, leaving space between them to encourage browning.
Roast. Roast for 20 to 25 minutes, or until the Brussels sprouts are tender inside and deeply golden and crispy around the edges.
Toast the pecans. While the Brussels sprouts roast, place the chopped pecans in a dry skillet over medium-low heat. Toast for 3 to 5 minutes, stirring frequently, until fragrant and lightly browned. Remove from the heat immediately to prevent burning.
Combine the ingredients. Transfer the roasted Brussels sprouts to a large serving bowl. Add the dried cranberries and toasted pecans.
Add the balsamic glaze. Drizzle the balsamic glaze over the Brussels sprouts and gently toss to coat. If you prefer a sweeter flavor, add the maple syrup and toss again.
Adjust the seasoning. Taste and add more salt, black pepper, balsamic glaze, or red pepper flakes as desired.
Serve. Serve immediately while the Brussels sprouts are warm and crispy.