By America’S Test Kitchen The Associated Press
Green bean casserole is a holiday staple, so we set out to develop a version that could be assembled in advance to make our holiday cooking easier.
To ensure that the flavour of the casserole didn’t become dull in the freezer, we boosted flavour by using plenty of garlic, white wine and fragrant thyme. After testing a number of ways to par-cook the beans, we discovered that the easiest solution was also the best: simply add them raw.
Tossing the beans with a bit of cornstarch before putting them in the baking dish helped to thicken any liquid they exuded during cooking. We stuck with a classic crunchy topping of canned fried onions and bread crumbs.
Green Bean Casserole
Start to finish: 3 hours, 20 minutes (Active time: 45 minutes)
Topping:2 slices hearty white sandwich bread, torn into pieces
2 tablespoons unsalted butter, melted
1/4 teaspoon salt
2 cups canned fried onions
Casserole:3 tablespoons unsalted butter
10 ounces white mushrooms, trimmed and sliced thin
1 teaspoon salt
1/2 teaspoon pepper
6 garlic cloves, minced
1/2 teaspoon dried thyme
1/4 cup all-purpose flour
1 1/2 cups chicken broth
1 1/2 cups heavy cream
1/2 cup dry white wine
2 pounds green beans, trimmed and cut into 1-inch pieces
1/4 cup cornstarch
For the topping: Pulse bread, melted butter, and salt in food processor to coarse crumbs, about 6 pulses. Combine bread crumbs and fried onions in bowl. Set aside.
For the casserole: Adjust oven rack to middle position and heat oven to 400 F. Melt butter in 12-inch skillet over medium heat. Add mushrooms, salt, and pepper and cook until mushrooms release their liquid, about 5 minutes. Increase heat to medium-high and cook until liquid has evaporated, about 5 minutes. Add garlic and thyme and cook until fragrant, about 30 seconds. Stir in flour and cook until golden, about 1 minute. Slowly whisk in broth, cream, and wine and bring to boil. Reduce heat to medium and simmer, stirring occasionally, until sauce is thickened, about 10 minutes.
Toss green beans with cornstarch in large bowl and transfer to 13 by 9-inch baking dish. Pour warm mushroom mixture evenly over green beans. Let cool completely.
Cover with aluminum foil and bake until sauce is bubbling and green beans are tender, 40 to 50 minutes, stirring green beans halfway through baking. Remove foil and spread topping over green beans. Bake until golden brown, about 8 minutes. Serve.