Step 1

Preheat the oven to 425 degrees F.

Step 2

Place the chicken breasts in a large ziptop bag. Drizzle with 1 1/2 tablespoons olive oil, then add the garlic, 1 tablespoon rosemary, cinnamon, 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Zip the bag tightly, then shake and rub the bag to coat the chicken in the oil and spices. Set aside while you chop the vegetables and apples, or refrigerate for up to 1 day.

Step 3

Once chopped, place the Brussels sprouts, sweet potato, onion, and apple on a large, rimmed baking sheet. Drizzle with the remaining 1 1/2 tablespoons olive oil, then sprinkle with remaining 1/2 teaspoon kosher salt and 1/4 teaspoon black pepper. Toss to evenly coat, then spread into an even layer.

Step 4

Remove the chicken from the marinade and place on top of the apple and vegetables. Place in the oven and roast until the chicken is cooked through and the internal temperature reaches 160 to 165 degrees F, about 18 to 22 minutes, or until done. Once the chicken is cooked through, remove to a plate to rest and cover with foil to keep warm. Toss the apple and vegetables on the pan, then return the pan to the oven and continue baking until caramelized and tender, about 10 to 15 additional minutes. Sprinkle with the remaining 1 tablespoon fresh rosemary. Serve warm with the rested chicken.