Preheat oven to 400℉
In a small bowl, whisk together oil, balsamic, maple, mustard, rosemary, garlic powder, salt, and pepper.
Add to Brussels sprouts, tossing to coat, then spread on a parchment lined baking sheet, placing each sprout cut side down in a single layer.
Roast for 15 minutes, then stir in apples and walnuts, mixing well.
Roast for an additional 10 minutes or until Brussels sprouts are tender, apples are still slightly crisp and walnuts are golden.
Garnish with pomegranate seeds and serve immediately.