Preheat oven to 450F.Prepare chicken for baking by rinsing under water and trimming away the extra fat. Pat until dry with a paper towel inside and out.
Place in a shallow baking pan and rub with butter all over the chicken. Season generously with salt and pepper. Stuff with sliced lemon and garlic cloves. Tie the legs of the chicken together with kitchen twine.
Roast chicken for 30 minutes. Then remove from oven and brush with sweet plum sauce.
Reduce the temperature to 375F and return to the over for another hour. Continue to baste with plum sauce and pan juices every 15 minutes. Meat is done when the temperature of the meat reaches 170F and the juices run clear when the tip of a knife is inserted.
Let rest for 10 minutes before carving. Serve with sweet plum sauce.