Preheat oven to 400 degrees F. Peel and cut sweet potatoes into 1-inch cubes. Place in a large bowl, season with salt and pepper, add half the EVOO and toss to coat. Arrange the sweet potatoes on a baking sheet.
Cut Brussels sprouts in half and place in the bowl. Season with salt and pepper, add the remaining EVOO and toss to coat. Arrange the Brussels sprouts on the baking sheet and roast until tender. In general, Brussels sprouts will be tender in 15 - 20 minutes and sweet potatoes in 30 - 35 minutes.
Tie the Mulling Spices in cheesecloth and place in a small saucepan. Add balsamic vinegar and bring to boil over high heat, reduce to low and let simmer until reduced by half, about 10 minutes.
Place vegetables in a serving dish, sprinkle with pumpkin seeds and drizzle with the balsamic reduction.