2 1/2 to 3poundsbone-in skin-on chicken thighsabout 5 thighs
5sprigs fresh rosemaryplus additional chopped fresh rosemary for serving
Positions racks in the center and upper thirds of your oven, and preheat the oven to 425 degrees F.
Arrange the onion, apple slices, and Brussels sprouts in the center of a large, rimmed baking sheet. Top with 1 tablespoon oil, honey, mustard, ½ teaspoon salt, and ¼ teaspoon pepper. Toss to coat, then spread in an even layer.
Nestle the chicken onto the sheet pan towards its center, skin side up, moving the apple and vegetables aside as needed so that the chicken sits directly on the sheet pan. Pat the chicken dry, and season with the remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Drizzle the remaining 1 tablespoon of oil over the top. Lay a sprig of rosemary on top of each piece of chicken. (If you have more thighs than sprigs, cut the sprigs into pieces as needed and divvy them up.)
Bake the chicken and vegetables on the center rack for 15 minutes. Remove the pan from the oven, and use a spatula to stir the vegetables. Return the pan to the oven, and continue baking for 5 to 10 minutes, until the chicken is cooked through. It will register 165 degrees F on an instant-read thermometer inserted at the thickest part. If some pieces of the chicken finish sooner than others, remove them to a plate and continue cooking the remaining pieces until they are done. The apples will become very soft and break down, and the onions and Brussels sprouts will darken and become super crisp (this is the honey caramelizing).
Remove the pan from the oven, then remove and discard the rosemary springs. Return any chicken pieces you removed earlier to the pan. Turn the oven to broil. Place the pan on the upper third of the oven and broil for 2 to 3 minutes, until the skin is golden and crispy. (This step will crisp the veggies further, too; if you prefer them not to continue crisping, remove them from the pan prior to broiling, or place the chicken on a different lined baking sheet.)
Remove the pan from the oven, and season the chicken with an extra pinch of salt and chopped fresh rosemary. Serve the chicken hot with the apples and veggies.
TO STORE: Place cooked chicken and veggies in separate containers, and store in the refrigerator for up to two days.
TO REHEAT: Remove the leftovers from the refrigerator and let them come to room temperature. Place on a foil-lined baking sheet and warm in a 325-degree F oven for 10 to 15 minutes, or until heated through. Season with a bit of extra salt and more fresh rosemary as needed.
*MOREVEGGIES: The recipe, as written, yields a moderate amount of veggies per person. We like a generous serving, so I tend to double the Brussels sprouts, apple, and onion mixture (as well as the honey, mustard, oil, and salt and pepper that go on top of them). Then, bake the extra vegetables on a separate sheet pan at the same time as the chicken. Depending upon your oven, you may need to extend the baking time by a few minutes since it will be more crowded.