Preheat the oven to 450°F. Line 2 baking trays with parchment paper.
Place the trimmed and halved Brussels sprouts on one of the baking trays, drizzle with 3 tbsp olive oil and toss to coat evenly with your hands or a wooden spoon. Place in the oven for 25-30 minutes or until tender and some of the outer leaves are starting to crisp and get a bit of char, tossing once during baking.
Place the cranberries on the other baking tray, drizzle with 1 tbsp of olive and toss evenly to coat with your hands or a wooden spoon. Place in the oven for approximately 10 minutes or until they burst and have started to release their juices.
In a small mixing bowl, whisk together the remaining 3 tbsp olive oil, maple syrup, orange juice and mustard. Place the roasted Brussels sprouts, toasted pecans and cranberries in a medium sized serving bowl. Drizzle with the dressing and toss to coat. Add salt and pepper, to taste. Serve immediately.