If the stuffing inside the turkey doesn't reach 165 degrees by the time the bird is done, transfer it to a baking dish and bake until it does.
Turkey: Preheat oven to 450 degrees, with rack in lower third. Boil 1/2 cup cider in a small saucepan until reduced by half, about 5 minutes. Remove from heat; stir in molasses until combined. Season body and neck cavities of turkey generously with salt and pepper. Rub butter evenly over skin; season with salt and pepper. Let stand 30 minutes.
Stuffing: Meanwhile, melt butter in a large skillet over medium-high. Add onion, celery, apple, and garlic; season with 1 teaspoon salt and 1/4 teaspoon pepper. Cook, stirring occasionally, until onion is translucent, about 3 minutes. Add wine; bring to a boil and cook until reduced by half, about 2 minutes. Transfer mixture to a large bowl; toss with bread, walnuts, parsley, and 1 cup broth until combined. Fold in eggs.
Lightly pack half of stuffing into body and neck cavities of turkey. Toss remaining stuffing with remaining 1 cup broth; transfer to a lightly buttered 2-quart baking dish and cover with parchment-lined foil. Tie turkey legs together with twine. Transfer to a roasting pan fitted with a rack. Pour broth and remaining 3/4 cup cider into pan.
Roast turkey 30 minutes. Reduce heat to 350 degrees. Brush turkey with some of cider-molasses glaze. Continue roasting, brushing with more glaze every 20 minutes, until a thermometer inserted in thickest part of thigh (avoiding bone) and into stuffing registers 165 degrees, 1 hour, 30 minutes to 2 hours, depending on size of bird. (Add more broth as needed to prevent bottom of pan from scorching.) Transfer turkey to a carving board. Let stand 30 minutes.
Meanwhile, bake extra stuffing in baking dish 15 minutes. Uncover and continue baking until top is crisp and golden brown in spots, about 15 minutes more.
Gravy: Remove rack from roasting pan; skim excess fat from pan drippings with a large spoon. Heat pan across two burners over medium-high. Add wine and bring to a boil, scraping browned bits from bottom of pan with a wooden spoon. Add 2 1/2 cups broth; return to a boil. Whisk together remaining 1/4 cup broth and flour in a small bowl. Slowly pour flour mixture into pan, whisking constantly, until gravy thickens slightly, about 2 minutes. Remove from heat; stir in butter until combined. Strain gravy through a fine-mesh sieve; transfer to a gravy boat.
Remove twine from turkey and transfer to a platter. Garnish with apples, pears, and fennel. Carve turkey and serve, with stuffing and gravy alongside.