For the turkey: Preheat the oven to 350°F.
In a small bowl, mash the butter with the garlic, sage, poultry seasoning, and lemon zest until well combined.
In a large saute pan over medium-high heat, cook the bacon, turning as needed, until the fat has rendered and the bacon is golden and crispy, 8 to 10 minutes. Transfer the bacon to a paper towel-lined plate. When cool enough to handle, crumble the bacon into bite-sized pieces. Drain the fat and wipe out the pan.
In the same pan over medium heat, melt 2 tablespoons of the butter mixture. Add the onion, celery, 1 teaspoon of salt, and 1 teaspoon of pepper and cook until translucent, 3 to 4 minutes. Add the apple and kale and cook until the apples soften slightly and the kale begins to wilt. Add the wine and lemon juice and cook until the wine is reduced by about half, 2 to 3 minutes. Stir in the parsley. Remove the mixture to a large bowl.
To the large bowl with the vegetables, add the stuffing mix, crumbled cornbread, and crumbled bacon, tossing to combine. Pour in the broth and stir until the bread is no longer dry and everything is well combined.
On a large cutting board, place the turkey breast skin-side down. Use a boning knife, a sharp, small knife, or kitchen shears to cut out and remove the back bone. Save these bones for stock. Using the knife, cut along the ribs and the keel bone to remove the large piece of sternum bone from the meat. Work slowly, feeling along where the bone is connected to the breast meat to ensure you’re cutting as close to the bone as possible to avoid cutting into the meat. Keep slicing close to the bone, working your way down and in towards the center of the breast roast until you can lift the keel bone from the roast. Cut out the tenders and reserve. Starting from the center, butterfly both of the breasts by inserting the knife into the side of the breast and cutting it in half horizontally until it is almost cut in half and can be opened like a book.
Pat the entire turkey down with paper towels. Place the turkey breast skin-side down. Place the tenders in the center of the roast where there will be a curve. If the roast seems thick, cover it in plastic wrap and pound it with a meat tenderizer until flattened and even (about ½ inch). Rub the surface of the turkey with 2 tablespoons of the butter mixture and sprinkle with salt and pepper. Spread the stuffing mixture in an even layer, leaving a ½-inch border all around. Starting with one long side, tightly roll the turkey into a log and place seam-side down on the board. Use kitchen twine to tie the roll once down the entire length of the turkey and around the width at approximately 2-inch intervals.
Rub the entire roast with the remaining butter mixture and sprinkle with salt and pepper. Place the roast seam-side down on a rack set in a roasting pan.
Roast until the turkey is golden brown and crispy and the internal temperature is 160°F, 1 hour 10 minutes to 1 hour 30 minutes. Remove the turkey from the pan and place on a carving board, covered in foil, to rest.
For the gravy: Remove the rack from the roasting pan and place the pan over medium heat. Whisk the flour into the drippings and cook, stirring frequently, until the roux is golden brown. Gradually add the stock, whisking to break up any clumps. Bring to a gentle simmer. Cook, whisking frequently, until the gravy is smooth and thickened, about 3 minutes. Add salt and pepper to taste.
Cut the twine off the turkey and slice. Serve with warm gravy and extra parsley and black pepper, if you'd like.