Homemade Green Bean Casserole with Fried Onions

Homemade Green Bean Casserole

This from-scratch green bean casserole has long, crisp-tender beans and browned mushrooms in a creamy sauce, with a generous pile of homemade fried onion strings on top. Blanching and drying the beans, then thickening the sauce before baking, keeps the filling from turning watery. A small portion of the onions bakes with the casserole; the rest goes on just before serving so it stays crisp.

Ingredients for Homemade Green Bean Casserole

Makes 8 side-dish servings.

• 2 pounds fresh green beans, trimmed (about 900g)
• 1 large yellow onion, very thinly sliced (about 250g)
• 1/2 cup buttermilk (120g)
• 3/4 cup all-purpose flour, divided (90g)
• 1 1/2 teaspoons kosher salt, divided, plus more for the blanching water
• 1 teaspoon black pepper, divided
• About 3 cups neutral frying oil, such as vegetable or canola oil, or enough for a 1 to 1 1/2-inch depth
• 4 tablespoons unsalted butter, plus a little for the baking dish (about 55g for the sauce)
• 12 ounces cremini mushrooms, sliced (340g)
• 2 garlic cloves, minced
• 1 teaspoon fresh thyme leaves, plus a small sprig for garnish, if desired
• 1 1/2 cups whole milk (360g)
• 1/2 cup half-and-half (120g)
• 1/2 cup low-sodium chicken or vegetable broth (120g)

How to Make Green Bean Casserole

1. Blanch the beans: Heat the oven to 375°F (190°C) and lightly butter a 2-quart oval baking dish or 8-by-11-inch casserole dish. Bring a large pot of salted water to a boil. Cook the beans for 4 to 5 minutes, until bright green and barely crisp-tender. Transfer them immediately to ice water, then drain and dry thoroughly.
2. Fry the onion strings: Toss the onion slices with the buttermilk. In another bowl, mix 1/2 cup of the flour with 1/2 teaspoon of the salt and 1/2 teaspoon of the pepper. Lift the onions from the buttermilk and toss them in the flour mixture until coated and shaggy. Heat 1 to 1 1/2 inches of oil in a small deep saucepan or Dutch oven to about 375°F. Fry the onions in small batches for 2 to 4 minutes per batch, turning gently, until golden brown with darker curled edges. Drain on a wire rack or paper towels and set aside.
3. Brown the mushrooms: Melt 2 tablespoons of the butter in a 12-inch skillet over medium-high heat. Add the mushrooms and a pinch of the remaining salt. Cook for 8 to 10 minutes, stirring occasionally, until their liquid evaporates and their edges brown. Add the garlic and thyme leaves; cook for about 1 minute, until fragrant.
4. Thicken the sauce: Reduce the heat to medium and melt the remaining 2 tablespoons butter in the skillet. Stir in the remaining 1/4 cup flour and cook briefly, until it no longer smells raw. Gradually whisk in the milk, half-and-half, and broth. Simmer gently for 6 to 8 minutes, until the sauce coats a spoon and a spoon drawn through it leaves a brief trail. Season with the remaining salt and pepper. If the sauce is thin, simmer it a little longer; if too thick, loosen it with a splash of milk.
5. Assemble: Fold the dried beans into the mushroom sauce and spread them in the baking dish. Scatter about one-third of the fried onions over the top. Keep the rest separate and dry.
6. Bake: Bake uncovered for 20 to 25 minutes, starting to check around 18 minutes. The sauce should bubble at the edges and in a few spots near the center, and the center should be hot. Let the casserole rest for 5 to 10 minutes.
7. Finish: Pile the reserved onion strings over the casserole just before serving. Add the thyme sprig, if desired, and serve from the baking dish.

How to Keep the Filling Creamy and the Onions Crisp

The ice bath stops the beans from continuing to cook, while thorough drying keeps water from thinning the sauce. Let the mushrooms release their liquid and brown before adding the dairy. The sauce should already coat a spoon when it goes into the baking dish; the short bake is for heating the casserole, not thickening a watery filling.

Keep the frying oil near 375°F and avoid crowding the pot, which can leave the onion coating greasy or soft. Let the fried onions drain outside the casserole. Baking only a small portion on top and adding the rest after the casserole rests gives the finished dish a crisp, generous topping.

Make-Ahead and Bean Substitutions

Make ahead: Assemble the bean-and-sauce filling in the baking dish up to 24 hours ahead and refrigerate it without onions. Store fully cooled fried onions separately in an airtight container at room temperature, or fry them shortly before serving. Bake the chilled filling at 375°F until hot and bubbling, generally 30 to 35 minutes. Add a small portion of onions near the end if desired, then pile on the rest after baking. If the onions darken before the center is hot, loosely cover the dish with foil.

Bean substitutions: Thaw frozen green beans completely, pat them very dry, and skip blanching; they will be softer than fresh beans. Canned beans are already soft, so drain them well and start checking the casserole earlier, baking until the center is hot. To skip frying, use 1 1/2 to 2 cups store-bought crispy fried onions, reserving most until serving.

How to Store and Reheat Green Bean Casserole

Refrigerate cooled leftovers in an airtight container for up to 3 to 4 days. Store any extra fried onions separately when possible. Reheat the casserole covered at 350°F (175°C) until hot, about 20 to 30 minutes, then add crisp onions.

For longer storage, freeze the unbaked bean-and-sauce filling without onions for up to 1 month. Thaw overnight in the refrigerator, bake until hot and bubbling, and add crisp onions at the end. Freezing may soften the beans.

What to Serve with Green Bean Casserole

Serve alongside roast turkey or ham, with roasted garlic mashed potatoes. For a larger holiday spread, add sweet potato casserole with pecan crumble.

Nutrition

Approximate nutrition per side-dish serving (1/8 of the casserole): 265 calories, 7g protein, 16g fat, and 25g carbohydrates. Approximate values per 100g: 100 calories, 3g protein, 6g fat, and 9g carbohydrates. Estimates assume about 1/4 cup of frying oil is absorbed; the amount retained by the onions and the finished casserole’s weight will vary.