24 to 48 hours before cooking, rinse the turkey inside and out. Pat dry with paper towels. Mix the salt, pepper, garlic powder and onion powder in a small bowl. Liberally sprinkle the inside and outside of the turkey with the seasoning mix and place on a sheet pan; cover with plastic wrap. Refrigerate 24 to 48 hours. Eight to 10 hours before cooking, remove the plastic wrap and continue to refrigerate uncovered.
Mix the butter with the minced sage. Use your fingers to loosen under the skin of the turkey, then rub the butter under the skin. Let sit at room temperature for 1 hour. If any moisture forms on the turkey skin, pat dry with paper towels.
Preheat the oven to 350 degrees F.
Stuff the turkey's cavity with the onion, garlic and sage bundle. Truss the turkey with kitchen twine, place on a rack in a large roasting pan and put in the oven.
Combine the chicken stock, maple syrup and bay leaf in a small saucepan over low heat. Bring to a very low simmer, then remove from the heat. After 30 minutes of roasting time, begin basting the turkey every 30 minutes with this mixture.
The turkey is done when an instant-read thermometer registers 160 degrees F in the breast and 165 degrees F in the thigh, 15 to 20 minutes per pound of turkey (3 hours to 4 hours 40 minutes). Tent the turkey with foil and let rest 45 minutes to 1 hour. Carve and serve.