Our slimmed down version of this classic offers the creamy mushroom flavor, the sweet tang of onions, and the crunch you expect from Green Bean Casserole, with 60 percent less calories and 80 percent less fat
Preheat the oven to 400 degrees F. Put the shallots (in their skins) on a small baking dish, roast until soft, about 30 minutes. When cool enough to handle, skin and coarsely chop the shallots. Set aside.
Bring a medium-large saucepan of water to a boil over high heat. Add kosher salt, to taste. Add the green beans, and cook, uncovered, until crisp-tender and bright green, about 3 minutes. Drain the beans in a colander and rinse with cold water. Transfer the beans to a large bowl.
In the same saucepan, heat the oil over medium heat. Add the mushrooms, season with 1 teaspoon salt, cook, stirring occasionally, until browned, about 7 minutes. Add the mushrooms to the beans.
Melt the butter in a small saucepan over medium heat. Add the flour and cook, stirring with a wooden spoon, until golden, about 2 minutes. Slowly whisk in the broth, increase the heat to high, and bring to a boil. Add the shallots, 1 teaspoon of the thyme, and remaining 1/2 teaspoon of salt. Reduce the heat to maintain a simmer and cook until thickened, stirring occasionally, about 5 minutes. Pour the sauce over the vegetables and stir to combine evenly.
Spray a 2-quart baking dish with vegetable cooking spray. Transfer the vegetable mixture to the pan. Add the remaining 2 teaspoons of thyme to bread crumbs and scatter over the vegetables. Bake uncovered until the sauce bubbles and the crumbs brown, about 20 minutes.
3 to 4 medium shallots, in their skins
Kosher salt, plus 1 1/2 teaspoons
1 pound fresh green beans, stemmed, and halved crosswise
1 tablespoon extra-virgin olive oil
8 ounces cremini mushrooms, sliced (about 4 cups)
2 tablespoons unsalted butter
3 tablespoons all-purpose flour
1 1/2 cups mushroom, vegetable, or chicken broth (see Cook's Note)
3 teaspoons fresh thyme leaves
Freshly ground black pepper
Vegetable cooking spray
1 cup fresh bread crumbs