Preheat the oven to 400°F (200°C).
Rinse the quinoa in a fine-mesh strainer and drain well. In a medium saucepan, bring the quinoa and water to a boil. Reduce the heat to low, cover, and simmer for about 15-20 minutes or until the quinoa is tender and fluffy.
In a large bowl, toss the sweet potatoes, onion, and garlic with 1/2 tablespoon of the olive oil, salt, and pepper on a baking sheet. Roast in the oven for about 20-25 minutes or until the sweet potatoes are tender.
In a separate bowl, toss the Brussels sprouts with the remaining 1/2 tablespoon of olive oil, salt, and pepper on a baking sheet. Roast in the oven for about 20-25 minutes or until the Brussels sprouts are tender and caramelized.
In a large skillet, cook the chicken over medium-high heat for about 5-7 minutes per side or until cooked through.
In a large bowl, combine the cooked quinoa, roasted sweet potatoes, Brussels sprouts, chopped apple, walnuts, and cranberries.
Slice the cooked chicken and place on top of the quinoa mixture. Season with cinnamon and nutmeg to taste.