Preheat the oven to 425°F (220°C).
Remove the giblets from the chicken. Rinse it thoroughly inside and out, then pat dry with paper towels. Place the chicken breast-side up in a large roasting pan
Season the cavity with salt and pepper. Cut one lemon into quarters and place it inside the cavity along with the halved garlic cloves and 2–3 sprigs of rosemary.
Tie the legs together with kitchen twine to help the chicken cook evenly.
Melt the butter in the microwave or in a small saucepan. Brush the melted butter over the outside of the chicken, then season with salt and pepper. Tuck the wings underneath the chicken.
Roast the chicken for about 45 minutes, then baste it with the juices from the pan. Continue roasting for 20–25 more minutes, until the skin is golden brown and the juices run clear when you cut between the leg and thigh. If the chicken browns too quickly, lightly cover it with foil.
Remove the chicken from the oven and let it rest in the roasting pan for 10–15 minutes.
Transfer the chicken to a cutting board. Remove the lemon, garlic, and herbs from the cavity. Carve the chicken and serve on a platter, garnishing with extra rosemary sprigs and lemon slices if desired.
