unsalted butter, plus more for the baking dish and foil
large loaf Italian bread (about 1 pound), cut into 3⁄4-inch pieces (about 16 cups)
medium onions, halved and thinly sliced
kosher salt and black pepper
dry white wine
low-sodium chicken broth
large eggs, beaten
chopped fresh chives
fresh thyme leaves
- Heat oven to 375° F. Butter a 9-by-13-inch baking dish. Divide the bread between 2 rimmed baking sheets and bake until dry and crisp, 10 to 12 minutes.
- Meanwhile, melt the butter in a large skillet over medium heat. Add the onions, 1 teaspoon salt, and ¼ teaspoon pepper. Cook over medium-low heat, stirring occasionally, until deep golden brown, about 1 hour. Add the wine and cook until evaporated, 2 to 4 minutes; transfer to a large bowl and let cool for 10 minutes.
- Add the bread, broth, eggs, chives, thyme, and ½ teaspoon salt to the onions and toss to combine. Transfer to the prepared baking dish. Cover with buttered foil and bake for 20 minutes. Uncover and bake until browned, 20 to 30 minutes more.