Splitting a whole chicken lets the bird cook more quickly and evenly, and it can make for a more elegant presentation -- especially in the case of smaller birds, where each person is served one half. While you can purchase split chickens from some butchers, you can easily cut the chicken yourself at home. Marinate and cook chicken halves as you would a whole chicken.
You can split a chicken by either slicing it in half or by butterflying. To halve or butterfly a chicken, cut along both sides of the backbone with kitchen shears or a very sharp chef's knife. Remove the backbone, and flip the bird so the carcass is facing the cutting board, pulling apart the two sides to flatten the chicken. At this stage, the chicken is butterflied and can be cooked as is. To completely split the chicken, cut along the center ridge of the breast bone -- it will be mostly cartilage -- using either the shears or the chef's knife. Save the backbone and the breastbone, and use them when you make stock.
Marinating and Seasoning
Marinate chicken halves as you would whole chickens or thighs. For a simple, fast version of a bistro roast chicken, rub the bird with plenty of sea salt and freshly ground black pepper, using either softened butter or duck fat to help the seasoning stick to the chicken. A lighter option is to use Herbes de Provence, olive oil and salt. In all cases, let the marinade or the rub rest on the chicken for 15 minutes to give the flavors time develop. Chicken halves can be marinated -- covered in plastic wrap or placed in a sealed bag or container -- overnight in the fridge.
To roast a half chicken, preheat the oven to 375 degrees Fahrenheit. If you're not cooking your chicken half in the marinade or with other ingredients, such as cut root vegetables, place the chicken halves on a broiler pan. To ensure even cooking, keep them from touching. If you're cooking your chicken in the marinade or with other foods, use a rimmed baking dish that can comfortably hold all of the ingredients. Place the pan on a center rack in the oven, and cook for roughly 10 minutes per pound of chicken. A split, 3-pound chicken takes around 30 minutes.
Saucing and Doneness
Chicken halves are fully cooked when the internal temperature -- measured at the thickest part of the thigh -- reads 165 F on your food thermometer. The juices will run clear and the meat will be opaque and white, although meat from younger chickens may still be a little pink closer to the bone. Veins running through the chicken may continue releasing dark red blood even when fully cooked. Make a sauce or gravy from the juices leftover from roasting, adding flour or cornstarch to thicken and adjusting seasoning as needed. Serve the chicken halves whole -- one per person -- or carved, keeping the white and dark meats separate on a single platter. Leftover chicken can be stored in an airtight container in the refrigerator for three to four days.