Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Peel and cube the sweet potato into 1/2-inch pieces and halve the Brussels sprouts.
Cut the chicken breast into bite-sized chunks, ensuring they are roughly the same size as the potato cubes.
In a small mixing bowl, whisk together the olive oil, maple syrup, Dijon mustard, sea salt, black pepper, garlic powder, and cinnamon until well combined.
Place the chicken, sweet potatoes, and Brussels sprouts on the prepared sheet pan.
Drizzle the maple-dijon glaze over the ingredients and toss thoroughly with your hands or a spatula to coat every piece.
Spread the mixture out into a single layer, ensuring no pieces are overlapping so they roast rather than steam.
Roast for 20 to 25 minutes, tossing the ingredients halfway through, until the chicken is cooked through and the potatoes are tender with golden, caramelized edges.