• STEP 1

    Heat 1 tbsp of the butter and the oil in a large pan and fry the mushrooms for 10-15 mins until golden. Stir in the green beans and cook for another 3-4 mins until the beans turn bright green. Scoop out the veg onto a plate.

  • STEP 2

    Heat the oven to 200C/180C fan/gas 6. Melt the remaining butter in the pan until foaming. Remove from the heat briefly and sprinkle over the flour, stirring into the butter to make a golden brown paste. Return to the heat and add the milk, a splash at a time, continually stirring until all the milk has been added and you get a smooth, thick white sauce. Season well. Stir the beans and mushrooms into the white sauce, and spoon into a medium ovenproof dish.

  • STEP 3

    Scatter over the crispy onions, then bake for 20-30 mins until bubbling and golden, covering if the onions brown too quickly.

Where did green bean casserole come from?

More a gratin than a casserole, the original recipe was created by Dorcas Reilly of the Campbell’s home economics department in the USA in the 1950s. Her version used a can of cream of mushroom soup for the sauce (a shortcut that is still used in some recipes today). Since then, it has become a staple at the Thanksgiving table for many families every year.

How do I get a thick and creamy sauce?

To thicken your sauce so it coats the green beans, make sure you add the milk to your roux (the butter and flour paste) slowly and keep stirring on a low heat, bubbling gently, until it reaches the desired consistency. It’s also important to fry the mushrooms and beans for the full time specified in the recipe – this will make sure any excess water evaporates from the vegetables in the pan.

Can I make green bean casserole ahead of time?

Yes! It’s a great dish to prepare in advance so all you have to do on the day is sprinkle over the fried onions and bake it. It will keep in the fridge, unbaked, for two days. You can also freeze it unbaked for up to three months and defrost in the fridge overnight. In both cases, don’t add the friend onions until you’re ready to bake the dish as they’ll become soggy. Follow the instructions in the method, adding an extra 5 minutes to the cooking time.

Can I make it with a can of soup like the original recipe?

Yes – if you’re short of time, swap the white mushroom sauce for a can of cream of mushroom soup.

Where can I get crispy onions?

You can buy packs or tubs or crispy onions in most supermarkets or online. They’re sweet and crunchy, and perfect for topping a classic green bean casserole. If you can’t find any, or want to make your own, then thinly slice 1 red or white onion, and heat enough veg or sunflower oil to come 1-2 cm up the side of a large pan. When hot, fry the onions in batches until crisp, then drain on kitchen paper and sprinkle with salt.

How to serve green bean casserole

Green bean casserole makes a delicious side dish to serve with your classic roast dinner, as part of a Thanksgiving feast or even with humble bangers and mash. Take a look at our best Thanksgiving recipes and menu ideas plus our collection of Thanksgiving recipes to help you plan an American-inspired feast.

Tips for making green bean casserole:

  • If your white sauce is lumpy, just pass it through a fine sieve into a clean pan or bowl before mixing in the mushrooms and beans.
  • Taste your white sauce to make sure you get the seasoning right before baking, adding enough salt and black pepper to suit your taste.
  • Sprinkling with crispy onions before baking will give your dish a crunchy, golden-brown topping. Cover with foil if they’re browning too quickly.

Variations on a classic green bean casserole:

  • For an extra crispy topping, mix a handful of breadcrumbs or flaked almonds into the fried onions for the topping.
  • Replace the green beans with broccoli or cauliflower. If you’re using cauliflower, add a handful of chopped, fresh parsley for some colour.
  • For extra flavour, add strips of bacon or cubes of pancetta to the pan at the start of the recipe. Fry until crisp, then remove from the pan and fry the mushrooms. You can also add grated cheese to the sauce for more richness and flavour.
  • Turn this side dish into a main meal by adding some shredded, cooked chicken to the sauce. You can also add cooked pasta and top with a handful of grated cheese to transform it into a pasta bake.

Alternatives to a green bean casserole:

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