Preheat the oven to 450 degrees F.
Using a small bowl, stir together the butter, garlic, sage, thyme, rosemary and set aside.
Spatchcock the turkey by using the poultry shears, cut along both sides of the backbone until you are able to remove it completely. Save it to make gravy or store it in a freezer bag to make homemade stock.
Gently stretch open the cavity of the bird to reveal the breastbone inside. Carefully make a small incision in the bone using a knife. This will make it easier to flatten out the turkey.
Flip the turkey over, breast side up, and stretch it out as wide as it will allow.
Place both of your hands on both sides of the chest of the bird and press down firmly until you hear a snapping sound and the turkey is able to flatten out. Tuck the wing tips or cut them off if you prefer.
Use your hands to generously spread the herb butter all over the turkey. Don’t forget the area between the skin and meat.
Use a paper towel to pat the outside of the turkey to dry it of any excess moisture. Drizzle the olive oil evenly on top of the turkey. Spread with your hands to cover evenly. Evenly sprinkle on the cajun seasoning.
Place in a roasting pan or directly on the oven rack with a separate pan placed on the rack underneath to catch the drippings. If you placed directly on the rack, remove using a set of metal spatulas or turkey lifters.
Cook the turkey for 30 minutes. Remove from the oven and brush evenly all over with maple syrup. Reduce the oven temperature to 350 degrees F. Return the turkey to the oven to cook.
Set a timer to check the turkey every 20 minutes by inserting a thermometer into the thickest part of the thigh, once the internal temperature registers 165 to 170 degrees it is ready to be removed.
Remove the turkey from the oven. If you used the roast pan loosely tent the pan with aluminum foil. If you cooked directly on the oven rack, carefully transfer the turkey from the oven onto a pan. Allow the turkey time to rest for 30 to 45 minutes before carving.