Remove, but do not discard, the large, fatty deposits found inside the flaps by the breast and tail cavities of the turkey.
In a 10-inch skillet, melt the turkey fat over high heat. Discard all but 1 tablespoon and return this to the skillet. Add the garlic and ½ teaspoon of the Poultry Magic, and sauté until the garlic just begins to turn brown and soft, about 2 to 3 minutes. Remove from the heat and drain. Blot with paper towels to remove any fat that may still remain, and set aside to cool.
Preheat the oven to 325°. Work your fingers between the breast meat and the skin to form pockets, and place the cooled sautéed garlic evenly inside these pockets. Sprinkle 2 teaspoons of the Poultry Magic inside the breast cavity, then place the vegetables inside the cavity. Position the carrots last because they're the easiest to put in.
Sprinkle the remaining Poultry Magic evenly over the outside of the turkey. Place the turkey in a large roasting pan and roast uncovered until tender and golden brown, about 3½ to 4½ hours. When the skin is light golden, about ⅔ done, shield the breast loosely with lightweight foil to prevent overcooking. Check for doneness ½ hour before turkey is expected to be done. Turkey is fully cooked when the thigh's internal temperature is 180° F. The thickest part of breast should read 170° F and the center of the stuffing should be at least 160° F.
When done, let the turkey stand for 15 to 20 minutes before carving.