Ingredients
6 medium yellow onions (6 to 8 ounces each), trimmed and halved crosswise, plus 1 small onion, finely chopped (3/4 cup)
Coarse salt
1/2 cup (1 stick) unsalted butter
3 1/2 cups fresh breadcrumbs (from about 9 slices white bread)
6 tablespoons fresh lemon juice
Preparation
Preheat oven to 400 degrees. Arrange onion halves in a large, nonreactive baking dish; season with salt. Add 3/4 cup water to dish. Cover with foil. Bake onions until tender, 40 to 45 minutes.
Meanwhile, melt butter in a large skillet over medium heat. Add chopped onion. Cook, stirring, until softened, about 4 minutes. Stir in breadcrumbs. Cook, stirring occasionally, until breadcrumbs are golden, about 3 minutes. Add lemon juice; season with salt.
Top onions with breadcrumb mixture, dividing evenly. Return to oven, and bake until topping is crisp and golden brown, 20 to 25 minutes more.
