Preparation

• Put the chicken on a cutting board breast side down. Use poultry shears to cut along both sides of the backbone; remove and discard the backbone. Flip the chicken over and press down gently to break the breastbone and flatten the breast slightly.

  In a gallon-size resealable plastic bag, combine the yogurt, garlic, shallot, parsley, dill, cracked peppercorns, lemon zest, and 2 tsp. salt. Add the chicken to the bag and turn to coat well. Set in a bowl and refrigerate overnight.

  Position a rack in the center of the oven and heat the oven to 450°F. Remove the chicken from the marinade and put it skin side up on a broiler pan or on a rack set inside a rimmed baking sheet. Season both sides well with salt and pepper. Roast the chicken, uncovered, until an instant-read thermometer inserted in the thigh reads 170°F, 45 to 50 minutes. Transfer the chicken to a carving board and loosely tent it with foil; let rest for 10 minutes before carving.