Preheat oven to 425°F. Line a large rimmed baking sheet with parchment paper.
In a large bowl, toss the sweet potatoes and Brussels sprouts with 1 tablespoon olive oil and half the salt and pepper. Spread in a single layer on the sheet, cut sides down.
Roast for 15 minutes.
Meanwhile, whisk the maple syrup, Dijon, garlic, rosemary and remaining 1 tablespoon olive oil in a small bowl. Pat the chicken dry and season with the remaining salt and pepper.
Pull the sheet from the oven, push the vegetables to the edges, set the chicken in the center, and brush everything generously with the maple-Dijon glaze.
Return to the oven and roast 15-18 minutes, until the chicken reaches 165°F in the center and the vegetables are tender and caramelized.
Optional: broil 1-2 minutes for extra color, watching closely so the glaze does not burn.
Rest the chicken 5 minutes, slice, and spoon the pan juices over the vegetables before serving.