Let the chicken sit at room temperature for 20 minutes. Preheat the oven to 425 degrees F with a rack in the lower center position.

In a small bowl, mix together the softened butter, Italian seasoning, garlic powder, salt, and pepper until combined. Set aside.

Scatter the sliced onion and chopped carrots across the bottom of a large cast iron skillet or roasting pan in an even layer.

Remove the chicken from packaging and discard any giblet packet. Pat the chicken completely dry with paper towels. Place breast side up on top of the vegetables and tuck the wings under the body. Stuff the lemon pieces and herb sprigs into the cavity.

Use a small spoon to loosen the skin from the breast meat. Push a spoonful of herb butter under the skin on each breast and rub to spread. Rub the remaining butter all over the outside of the chicken.

Optional: tie the legs together with kitchen twine close to the body. Without trussing, the chicken may cook 10 to 15 minutes faster, so check the internal temperature earlier.

Pour 3/4 cup of water, chicken broth, or white wine into the bottom of the pan.

Roast at 425 degrees F for 65 to 90 minutes. A 3.5-pound bird typically reaches temperature around 65 minutes; a 5-pound bird closer to 90. Cook until an instant-read thermometer inserted into the thickest part of the thigh, not touching bone, reads 165 degrees F. If the skin browns too quickly, tent loosely with foil and remove it for the last 5 to 10 minutes.

Transfer to a cutting board and let the chicken rest uncovered for 15 minutes before carving. Resting allows the juices to redistribute so every slice stays moist.