Preheat the oven to 350 degrees . Mix together the softened butter, fennel seeds and sage and season with salt and pepper. Carefully slide your hands under the skin of the turkey pieces until it separates from the flesh, then spread the herb butter evenly between the meat and skin. Season the turkey pieces with salt and pepper. Place the pieces, skin side up, in a single layer in a large roasting pan outfitted with a rack. Transfer to the oven.
After 15 minutes, baste the turkey with the melted butter. Continue basting every 15 minutes, until both breast and legs reach an internal temperature of 165 degrees when a thermometer is inserted in the thickest parts, 1 to 1 1/2 hours. Remove the turkey from the oven and tent loosely with aluminum foil. Let it rest for 15 minutes before carving.