Old-Fashioned Green Bean Casserole
Green bean casserole is the dish that means the holidays are really here — the one that appears on the table every Thanksgiving and Christmas, scraped clean before the turkey's even carved. It was born in 1955 in a soup-company test kitchen, made with a tin of mushroom soup and a can of fried onions, and there is no shame in that version. But once you've made it with a proper mushroom sauce from scratch, you'll never go back — it's the same comforting casserole, only deeper, creamier and tasting of real mushrooms.
Two small things lift it above the crowd. First, blanch the beans — a few minutes in boiling water then straight into cold — so they keep their colour and a little bite instead of going grey and limp in the oven. Second, hold the crispy onions back: stir half through if you like, but scatter the rest on only for the last ten minutes so they stay shatteringly crisp rather than turning soft under the sauce.
Make the sauce as simple or as grand as you like — good shop-bought crispy onions are entirely traditional, but a handful of homemade ones takes it over the top. It can be built ahead and baked when you need it, which on a busy holiday morning is worth its weight in gold.
Old-Fashioned Green Bean Casserole
Crisp-tender beans in a real mushroom cream sauce under a crown of crispy fried onions.
Ingredients
- 700 g green beans, trimmed and halved
- 40 g butter
- 300 g mushrooms, sliced
- 1 onion, finely chopped, plus 2 garlic cloves
- 3 tbsp plain flour
- 300 ml chicken or vegetable stock
- 250 ml whole milk or single cream
- 1 tsp soy sauce, salt and black pepper
- 120 g crispy fried onions
Method
- Blanch the beans. Boil the green beans in well-salted water for 4–5 minutes until just crisp-tender, then drain and plunge into cold water. This keeps them green. Drain well and tip into a 23×33 cm dish.
- Cook the mushrooms. Melt the butter in a large pan and fry the mushrooms over a good heat until golden and their liquid has cooked away, then add the onion and garlic and soften for 5 minutes.
- Make the sauce. Stir in the flour and cook 1 minute, then gradually whisk in the stock and milk. Simmer, stirring, until thickened and creamy. Add the soy sauce, salt & plenty of pepper — it should taste well seasoned.
- Combine. Pour the sauce over the beans and fold together with half the crispy onions. Level the top.
- Bake. Bake at 200°C (fan 180°C / gas 6) for 20 minutes, until bubbling. Scatter over the remaining crispy onions and bake 8–10 minutes more, until golden and crunchy.
- Serve. Rest a few minutes and serve hot, straight from the dish.
Build the whole casserole a day ahead and keep it covered in the fridge — but add the crispy onions only just before it bakes, or they turn to disappointment. Bring it to room temperature first so it heats through evenly.
Tips for the best casserole
Blanch, don't boil to death
A few minutes then straight into cold water keeps the beans green and crisp-tender instead of grey and soft.
Brown the mushrooms properly
Cook them until golden and the water's gone before adding onion — that's where the deep mushroom flavour comes from.
Onions on last
Scatter most of the crispy onions on for only the final ten minutes so they stay shatteringly crunchy, not soggy.
Questions, answered
Can I make green bean casserole ahead of time?
Yes — it's a holiday lifesaver. Assemble it completely (sauce and beans) up to a day ahead and refrigerate, but add the crispy onions only just before baking. Let it come to room temperature first, then bake as usual, adding a few extra minutes if it's fridge-cold.
Can I use frozen or tinned green beans?
Frozen beans work well — thaw and drain them and skip the blanching. Tinned green beans are the old-school choice and fine in a pinch; drain them thoroughly and just fold into the sauce, as they're already soft and need no blanching.
Why is my casserole watery?
Usually wet beans or under-thickened sauce. Drain blanched or tinned beans really well, and simmer the sauce until it's properly thick and coats the spoon before it goes in — it loosens again in the oven, so it should look a touch too thick to start.
Can I still use tinned mushroom soup?
Of course — that's the original 1955 recipe. Stir a 295 g tin of condensed mushroom soup with a splash of milk and the soy sauce, fold through the beans and half the onions, and bake. The from-scratch sauce here just tastes deeper and less salty.