1 jar (7 ounces) dry-packed cooked chestnuts, coarsely crumbled
3 large eggs, lightly beaten
Preheat oven to 375 degrees. Butter an 8-inch square baking dish; set aside. Arrange bread in a single layer on two rimmed baking sheets. Bake until dried, rotating sheets from top to bottom and front to back halfway through, about 15 minutes. Meanwhile, in a large saucepan over medium heat, melt butter. Add onions and celery; season with salt and pepper. Cook, stirring occasionally, until tender, 4 to 6 minutes. Add apples; cook until softened, about 3 minutes. Transfer mixture to a large bowl; reserve saucepan.
In same saucepan, bring broth to a boil. Remove from heat; set aside. To onion-apple mixture, add bread, sage, chestnuts, and eggs. Season with salt and pepper; toss to combine. Add half the broth and toss to combine. Continue adding broth and tossing just until stuffing is moistened but not wet.
Place about 4 cups stuffing in turkey. Spoon remaining stuffing into prepared baking dish; cover with buttered aluminum foil and refrigerate. When turkey is removed from oven, place covered baking dish in oven, and bake until warmed through, 25 to 30 minutes. Uncover and bake until golden, about 15 minutes more.