Combine first 6 ingredients in a small bowl.
Remove giblets and neck from turkey; discard or reserve for another use. Dry the turkey's skin with paper towels. Do not rinse.
Place turkey, breast side down, on a large, stable cutting board. Using kitchen shears, cut along both sides of the backbone; discard backbone or reserve for another use.
Turn turkey breast side up. Press firmly against the breastbone with the heel of your hand. The bird will be splayed open, butterfly style.
Trim any excess fat or skin. Tuck wing tips under the breast. Arrange the thighs toward the center of the turkey. Place turkey in a large roasting pan.
Rub spice mixture under skin on. For best results and crispy skin, loosely cover, and refrigerate 8 to 24 hours.
Heat oven to 450°F. Line a clean baking pan with foil, and pour about 1 cup of water into the pan. Place a roasting rack in the pan. Move the turkey to the roasting rack.
Bake for 70 minutes at 450°F. After 70 minutes, check the turkey's internal temperature with an instant-read thermometer. Cook in 15-minute increments until the thermometer inserted into the thickest part of the thigh registers 160°F. Remove baking pan, and place turkey on a cutting board. Let stand, loosely covered with foil, 30 minutes.
