Light your grill and set up for indirect heat, allow the grill to preheat and establish temperature at 350°F.
While the grill is preheating, combine all ingredients for the turkey seasoning in a mixing bowl. Whisk together and set aside.
Remove turkey from wrapping, and rinse under cold water. Divide the turkey in half by removing the spine with kitchen shears, then cut the turkey down the middle of the breast bone to form two equal halves of the turkey. Using the sheers, cut off the wing tips.
Place the turkey halves on a large baking sheet and pat them completely dry with paper towels. Coat both halves with olive oil, then season with turkey seasoning, being sure to get under the wings and ensuring the skin is evenly coated.
Place the turkey on the grill skin side up, over indirect heat. Close the lid and allow the turkey to roast for 30 minutes.
While the turkey is roasting, melt two sticks of butter over medium heat. Allow the butter to foam and the milk solids to slightly brown at the bottom of the pan. When the foaming has stopped, remove from heat, add the chopped sage and whisk together. Divide the melted butter in half and keep warm, allowing the sage to seep.
After 30 minutes of roasting, use a basting brush to lightly baste the turkey skin with half of the brown sage butter. Repeat every 10 minutes until the turkey has reached the desired internal temperature as indicated by a reliable instant read thermometer. About 30 minutes longer.
Remove the turkey from the grill. Use a sharp knife to separate the thigh and leg portion, and remove the wings. Then remove the breast meat from the breast bone, and slice it across the breast.
Plate the turkey on a large platter, and evenly pour the remaining half of the sage brown butter on the turkey to serve.