01 - Preheat the oven to 350°F.
02 - Combine softened butter, garlic, parsley, sage, rosemary, thyme, lemon zest, salt, and pepper in a small bowl until well blended.
03 - Pat turkey breast dry with paper towels. Gently separate skin from the meat and spread half of the herb butter beneath the skin. Rub remaining butter evenly over the outside.
04 - Place lemon and onion slices in the bottom of a roasting pan. Position the turkey breast on top, skin side up. Pour chicken broth or water into the pan.
05 - Roast uncovered for 60 to 75 minutes until internal temperature reaches 165°F. Baste with pan juices halfway through cooking. Cover loosely with foil if skin browns too rapidly.
06 - Remove from oven and let rest for 15 minutes before slicing. Serve with pan juices.