01 - Preheat oven to 400°F.
02 - Arrange onion slices and carrot chunks in the bottom of a large roasting pan to create a flavorful bed for the chicken.
03 - Rub the entire chicken surface with olive oil, then evenly coat with kosher salt, black pepper, and lemon zest.
04 - Fill the chicken cavity with halved lemons, halved garlic bulb, and fresh thyme sprigs.
05 - Secure the legs together with kitchen twine and tuck wing tips under the body for even cooking.
06 - Place the chicken breast-side up directly on the vegetable bed in the roasting pan.
07 - Roast for 1 hour 10 minutes, basting with pan juices once or twice during cooking, until juices run clear and internal temperature reaches 165°F when measured at the thickest part of the thigh.
08 - Let chicken rest for 10 minutes before carving to allow juices to redistribute. Serve with pan juices and roasted vegetables from the pan.