Finely grate peel from lemon and juice lemon. In a microwave, melt butter. Stir in lemon juice and peel, rosemary, garlic, salt and pepper.
Grill chicken, covered, over medium heat or broil 4 in. from heat 5-7 minutes on each side or until a thermometer reads 165°, basting frequently with butter mixture during the last 5 minutes of cooking.
