Preheat the oven to 400°F (200°C).
In a large bowl, combine the olive oil, Dijon mustard, maple syrup, garlic powder, salt, and pepper. Whisk until well blended.
Add the halved Brussels sprouts to the bowl and toss until they are evenly coated with the maple Dijon mixture.
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, or until the Brussels sprouts are tender and caramelized, stirring halfway through for even cooking.
If using, sprinkle the chopped pecans and dried cranberries over the Brussels sprouts during the last 5 minutes of roasting.
Remove from the oven and serve warm.