Preheat the oven to 350 degrees F and place the oven rack 1 level lower than the center of the oven.
Mix the butter, garlic, salt and pepper together in a small mixing bowl.
Remove the neck and giblets from the turkey and tuck the wings under the turkey. You can tie back the wings of the turkey if you prefer.
Rub the butter mixture all over the skin of the turkey.
Place the flour into the oven bag and shake the bag to coat the inside of the bag with the flour.
Then place the onion, carrots and celery into the oven bag and then place the turkey into the oven bag on top of the vegetables.
Close the oven bag with the tie included with the bag and place the bag with the all the ingredients onto a roasted pan.
Cut slits in the top of the oven bag to allow the steam to escape.
Cook the turkey based on the size of the turkey and use a meat thermometer to ensure that the turkey reaches an internal temperature of 165 degrees F. A 12-15 lb turkey will take approximately 2 to 2 1/2 hours. A 15-20 lb turkey will take approximately 2 1/2 – 3 hours. A 20-24 lb turkey will take approximately 3 – 3 1/2 hours.
Let the turkey rest for 20 minutes. Then carefully cut the oven bag off the turkey.
Remove the turkey to a serving platter, carve and enjoy!
Video
Notes
To thaw a turkey properly, allow 24 hours for every 5 pounds of turkey to thaw in a refrigerator.