TO MAKE THE APPLE-BOURBON TURKEY
Step 1 (12-24 HOURS BEFORE) - Stir together apple juice, bourbon and light brown sugar, stirring until sugar dissolves. This creates the apple-bourbon marinade.
Step 2 (12-24 HOURS BEFORE) - Remove giblets** and neck from turkey (YouTube has some brilliant tutorials on how to do this!) and rinse the turkey with cold water. Drain cavity well and pat dry. Place turkey in a large roasting pan. Dip cheesecloth into the apple juice mixture, then wring dry. Cover turkey with cheesecloth then pour apple juice mixture over cheesecloth, coating completely. Cover and chill 12 to 24 hours, basting occasionally with marinade.
Step 3 - Preheat oven to 170 degrees Celsius. Remove turkey from pan, discarding cheesecloth and reserving 3 cups of the apple-bourbon marinade. Sprinkle turkey cavity with desired amount of salt; rub into cavity. Sprinkle desired amount of salt and freshly ground pepper onto the skin and rub into skin. Tie ends of legs together with string; tuck wingtips under.
Step 4 - Arrange the celery, carrots, halved apples and chopped onions in a single layer in bottom of roasting pan. Place turkey, breast side up, on celery mixture; pour reserved marinade over turkey in pan.
Step 5 - Bake at 170 degrees Celsius for 3 ¼ hours to 4 hours, basting every 30 minutes with pan juices and shielding with tin foil after 2 ½ hours to prevent excessive browning (if necessary). Remove from oven, and let stand 30 minutes. IMPORTANT - Check the thickest part of the turkey and check to see that the meat is cooked through – it should be white, not pink!
Step 6 - Transfer the turkey to a serving platter, reserving 2 ½ cups of pan drippings. Pour reserved drippings through a fine wire-mesh strainer into a large measuring cup, discarding solids.
TO MAKE THE GRAVY
Step 7 - Melt butter in a saucepan over medium heat; whisk in flour, and cook for 1-2 minutes, whisking constantly until smooth. Gradually add drippings, and bring to a boil. Reduce heat to medium, and simmer for up to 5 minutes, stirring mixture occasionally, until gravy thickens. Stir in salt and freshly ground pepper to taste. Serve turkey with warm gravy.
*Frozen whole turkey, thawed, may be substituted.
** Giblets = the liver, heart, gizzard, and neck of a chicken or other fowl, usually removed before the bird is cooked, and often used to make gravy, stuffing, or soup.