Caramelized Onion Stuffng with Apples and Sage

Heat oven to 375 degrees F. Oil a 3-quart baking dish. Place the bread on a rimmed baking sheet and bake until dry and beginning to turn golden brown, 20 to 25 minutes. Transfer to a large bowl. Meanwhile, heat 3 tablespoons oil in a large skillet over medium heat. Add the onions, season with 3/4 teaspoon salt and 1/2 teaspoon pepper, and cook, covered, stirring occasionally, for 10 minutes. Add the celery and parsnips and cook, uncovered, stirring occasionally, until the vegetables are tender and the onions are beginning to brown, 8 to 10 minutes more. Stir in the garlic and cook for 1 minute. Add the parsley and sage and cook, stirring, for 1 minute more; remove from heat. Pour the broth over the toasted bread and toss until nearly absorbed. Add the vegetable mixture and the apples and mix to combine. Fold in the egg, then transfer the mixture to the prepared baking dish. Cover loosely with oiled foil and bake for 25 minutes. Uncover and bake until golden brown, 15 to 20 minutes more.