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Green Bean Casserole

Fresh green beans blanched bright, folded into a mushroom cream sauce built in one skillet, and baked under a thick crown of crispy fried onions.

Prep
25 min
Cook
40 min
Rest
5 min
Makes
Serves 8
Jump to the recipe
Green beans topped with crispy fried onions on a white plate
Photo: FOX ^.ᆽ.^= ∫ / Pexels

Green bean casserole has three parts, and each one fails in its own way. The beans go gray and soft if they cook too long before the oven. The sauce goes gluey or thin depending on how the flour is handled. And the onions on top either stay crisp or turn into a damp, chewy lid. Get those three right and the dish stops being the thing people take a polite spoonful of.

Start with the beans. Fresh beans blanched for four minutes in heavily salted water, then plunged into ice water, keep their color and a little snap even after half an hour in the oven. Skip the ice bath and they carry on cooking from their own heat, which is how a casserole ends up olive drab. Frozen cut beans work too, and they need no blanching at all: thaw them, pat them dry, and they go straight into the sauce. Canned beans are already soft, so they only get softer.

The sauce is a quick mushroom cream sauce, built in the same skillet. Mushrooms cooked in butter until their liquid has evaporated and they have browned, then a little flour stirred in, then broth and cream whisked in slowly. The browning matters more than any seasoning you add later; pale, steamed mushrooms taste of almost nothing. Give them room in a wide skillet and leave them alone for a few minutes at a time so they color instead of stewing.

Flour is where the texture is decided. Three tablespoons to two cups of liquid gives a sauce that coats the beans and still flows when you spoon it out. More than that and it sets into a paste as it cools on the table. If the sauce looks thin in the skillet, trust it: it thickens in the oven as the beans give up a little water and the cream reduces at the edges.

The fried onions go on in two stages. Half are stirred into the casserole, where they soften and season the sauce from inside, which is the flavor most people remember from childhood versions. The other half go on top for the last ten minutes only. Put them on at the start and they scorch at the edges long before the middle is hot.

Like most Thanksgiving sides, it holds well. Assemble the beans and sauce a day ahead, keep the topping separate, and bake it when the turkey comes out to rest.

On the same table, slow cooker garlic herb potatoes free up the oven entirely, and cranberry pecan slaw brings the crunch and acidity a rich holiday plate is usually missing. For a second oven side, scalloped potatoes bake at the same temperature.

A roast turkey on a holiday table with green beans and mashed potatoes
Photo: Rufina Rusakova / Pexels

Green bean casserole, ready for the oven

Fresh green beans blanched bright, folded into a mushroom cream sauce built in one skillet, and baked under a thick crown of crispy fried onions.

Beans, sauce and the onion crown

For the beans

  • 2 lb (900 g) fresh green beans, trimmed and cut into 2 in (5 cm) pieces
  • 2 tbsp kosher salt, for the blanching water

For the mushroom sauce

  • 3 tbsp (45 g) unsalted butter
  • 10 oz (285 g) cremini mushrooms, thinly sliced
  • 1 small yellow onion, finely diced
  • 2 cloves garlic, minced
  • 3 tbsp (25 g) all-purpose flour
  • 1 cup (240 ml) chicken or vegetable broth
  • 1 cup (240 ml) heavy cream
  • 1 tsp soy sauce
  • ½ tsp fine salt, plus more to taste
  • ¼ tsp black pepper
  • ¼ tsp ground nutmeg

For the topping

  • 2⅔ cups (170 g) crispy fried onions, divided
  • ¼ cup (25 g) Parmesan, finely grated (optional)

Blanch, brown the mushrooms, bake twice

  1. 1 Heat the oven to 375°F (190°C) and butter a 9×13 in (23×33 cm) baking dish. Bring a large pot of water to a boil with the kosher salt and set a big bowl of ice water next to the stove.
  2. 2 Boil the green beans for 4 minutes, until bright green and just tender. Drain and plunge them into the ice water, then drain again and spread on a kitchen towel to dry.
  3. 3 Melt the butter in a large skillet over medium-high heat. Add the mushrooms in an even layer and cook, stirring only every few minutes, until their liquid has evaporated and they are browned, 8–10 minutes.
  4. 4 Add the onion and cook 3 minutes until soft, then the garlic for 30 seconds. Sprinkle in the flour and stir for 1 minute so it coats everything and loses its raw smell.
  5. 5 Slowly pour in the broth while stirring, then the cream. Add the soy sauce, salt, pepper and nutmeg. Simmer, stirring, until the sauce thickens enough to coat a spoon, about 3 minutes. Taste for salt.
  6. 6 Take the skillet off the heat and fold in the green beans and half of the fried onions. Spread in the baking dish.
  7. 7 Bake for 20 minutes, until bubbling at the edges. Scatter the remaining fried onions and the Parmesan, if using, over the top and bake 8–10 minutes more, until the onions are deep golden.
  8. 8 Let the casserole rest 5 minutes before serving so the sauce settles.

Frozen beans, homemade onions and making it ahead

  • Frozen beans: use two 16 oz (450 g) bags of cut green beans. Thaw, pat completely dry and skip the blanching.
  • Make ahead: assemble through step 6 without the onions folded in, cover and refrigerate up to 2 days. Stir in half the onions just before baking and add 10 minutes to the first bake.
  • Homemade onions: toss 1 thinly sliced onion in ¼ cup (30 g) flour with a pinch of salt and fry in ½ in (1 cm) of oil at 350°F (175°C) until golden, 3–4 minutes. Drain well before using.
  • Gluten-free: thicken with 1 tbsp cornstarch whisked into the cold broth instead of flour, and use gluten-free fried onions.
  • Leftovers: keep covered in the refrigerator up to 4 days. Reheat at 350°F (180°C) for 15 minutes; the topping will soften but recrisps a little uncovered.

Canned soup, watery sauce and gray beans

Yes. Two 10.5 oz (300 g) cans with ½ cup (120 ml) milk replace the whole sauce. It will be saltier and less mushroomy, so skip the added salt and soy sauce and taste before baking.

Usually the beans went in wet, or the mushrooms were not cooked until their liquid evaporated. Both release water in the oven and thin the sauce. Dry the blanched beans on a towel and brown the mushrooms properly.

The beans and sauce can be kept warm in a slow cooker on low for up to 2 hours, which helps on a crowded holiday. Toast the onions separately in a dry skillet and scatter them over just before serving; they never crisp under a lid.

Blanch them short, about 4 minutes, and shock them in ice water so they stop cooking. Overcooked beans turn olive in the oven no matter what else you do.

Yes. Build the sauce in a large Dutch oven and bake in two 9×13 in (23×33 cm) dishes rather than one deep one, so the middle heats through before the edges overcook.