Spatchcocking, or butterflying the chicken, helps it cook more quickly and more evenly, and since all the skin faces up, it browns beautifully. Add your favorite hearty veggies to the baking sheet along with some lemon halves, which you can turn into a lemon vinaigrette for serving.
1 whole chicken, 5 to 6 pounds
Extra-virgin olive oil
2 tablespoons finely chopped fresh rosemary or 2 teaspoons dried rosemary
Salt and freshly ground black pepper
2 small onions, peeled and quartered
4 carrots, peeled and cut into 1-inch chunks
2 medium potatoes, cut into 1-inch chunks
2 lemons, halved
1 teaspoon Dijon mustard
1Prep: Heat the oven to 400°F (204°C). Line a large rimmed baking sheet with aluminum foil or parchment paper.
2Spatchcock the chicken: Place the chicken with the backbone facing up and the drumsticks pointing toward you. Using poultry shears or sharp kitchen scissors, cut down one side of the backbone, then the other, to remove it. Flip the chicken so it is skin-side up, then press firmly on the breastbone until it cracks and the chicken flattens.
3Season the chicken: Rub both sides of the chicken with a little olive oil, then season generously with salt, pepper, and about 1 tablespoon of the rosemary. Transfer the chicken to the prepared baking sheet, breast-side up, and tuck the wing tips underneath.
4Prepare the vegetables: Toss the onions, carrots, and potatoes with 1 tablespoon of olive oil, the remaining rosemary, and a pinch of salt and pepper. Scatter the vegetables around the chicken. Add the lemon halves to the baking sheet.
5Roast: Roast the chicken until an instant-read thermometer inserted into the thickest part of the thigh reaches 165°F, about 1 hour. After 30 minutes, rotate the baking sheet and toss the vegetables for even cooking.
6Rest the chicken: Transfer the chicken to a cutting board, tent loosely with foil, and let rest for about 10 minutes. Keep veggies warm covered with foil.
7Make the vinaigrette: Use tongs to squeeze the roasted lemons into a small bowl. Add any juices from the baking sheet. Whisk in the mustard. Taste, then add a little olive oil (about 1 tablespoon), salt, and pepper as needed.
8Serve: Slice the chicken or cut it into quarters. Serve with the roasted vegetables and spoon the roasted lemon vinaigrette over the top.