Be sure to cut the vegetables about the same size so that they cook at the same rate and toss them at least once while they are in the oven.
Preheat the oven to 425°. Spread the pecans in a pie plate and toast until fragrant, about 6 minutes. Let cool.
In a large bowl, toss the carrots, parsnips, cauliflower, squash and brussels sprouts with the olive oil and nutmeg and season generously with salt and black pepper. Spread the vegetables on 2 large rimmed baking sheets and roast for 30 minutes, until the vegetables begin to brown.
Scatter the pecans and ginger over the vegetables and drizzle with the maple syrup; toss well. Continue to roast the vegetables for 25 minutes longer, until they are tender and golden. Scrape the vegetables into a bowl and serve hot or at room temperature.
The roasted vegetables can be kept at room temperature for up to two hours before serving.