Rinse the chicken and pat dry. Zest the lemon. Slice remaining lemon into quarters and place to the side. In a medium bowl, combine butter, lemon zest, minced garlic and 1/4 cup chopped rosemary, 1 teaspoon salt and 1/2 teaspoon pepper.
Take your hand and slide the butter mixture between the skin and the meat on the breast, as well as loosening the 'pockets' between the leg and wing joints and inserting the butter there.
Season the outside of the chicken and the cavity with the salt and pepper . Add the quartered lemon and rosemary sprigs to the chicken cavity. Bind the legs with twine and tuck the wings into the leg joints to secure.
Place the chicken breast up onto the roasting rack and into the oven. Roast for approximately 50 minutes, or until the juices run clear, basting occasionally with the pan juices. Let rest for 10 minutes. Carve and serve.