Green Bean Casserole with Creamy Mushroom Sauce and Crispy Onions
Why this recipe works
- Creamy homemade sauce: A simple roux thickens the milk into a smooth mushroom sauce that coats the beans without relying on canned soup.
- Tender beans, crisp topping: Blanching keeps the green beans tender-crisp, while adding the fried onions near the end preserves their crunch.
- Comforting side dish: Savoury mushrooms, creamy sauce and golden onions make it a natural partner for roast meats and festive meals.
Get the most out of this recipe
Ingredient notes
- Choosing mushrooms: Cremini mushrooms give the sauce a deeper savoury flavour; button mushrooms make a lighter, milder version.
- Milk choice: Whole milk gives the sauce better body. Low-fat milk can be used, but it may need a little longer at a gentle simmer to thicken.
- Drain the beans well: Excess water from the blanched beans can loosen the sauce, so let them drain thoroughly before mixing.
Common mistakes
- Overcooking the beans: Avoid boiling the beans until fully soft before baking; they should still have a little bite when they go into the sauce.
- Lumpy sauce: Whisk the milk into the roux gradually so the sauce stays smooth and evenly thickened.
- Catching the mushrooms: Keep the heat moderate while cooking the mushrooms so their liquid evaporates without the butter or flour scorching.
Make-ahead tips
- Keep the topping separate: If preparing ahead, keep the fried onions separate until the final bake so they stay crisp.
- Reheating: Reheat covered casserole in a 180°C (355°F) oven until piping hot, then add a fresh layer of fried onion for the best texture.
Serving ideas
- Serve with roasts: Pairs well with roast chicken, turkey, ham or other rich mains where a creamy vegetable side feels at home.
- Finish simply: A final grind of black pepper over the crisp onions adds a little sharpness without changing the character of the dish.
Equipment you'll need
Ingredients
Instructions
- Heat the oven to 190°C (375°F). Bring a large pot of well-salted water to the boil, add the green beans and cook for 4 to 5 minutes until bright green and just tender. Drain well in a colander and set aside.
- Melt the butter in a saucepan over a medium heat. Add the mushrooms and a pinch of the salt, then cook for 8 to 10 minutes, stirring, until the mushrooms have released their liquid and it has mostly evaporated. Keep the heat moderate so the mushrooms soften and lightly colour without burning.
- Stir in the flour and cook for 1 minute, stirring constantly, to make a roux. Gradually whisk in the milk until smooth. Simmer gently for 3 to 5 minutes, whisking often, until thick enough to coat the back of a spoon.
- Season the sauce with the remaining salt and the black pepper. Add the drained green beans and stir to coat. Tip into a baking dish and level the top.
- Bake for 18 to 20 minutes until bubbling around the edges. Scatter the fried onion evenly over the top. Bake for a further 5 to 7 minutes until the topping is crisp and golden.
Recipe notes
Tips
- For the best texture, keep the beans slightly undercooked before baking so they stay bright and tender-crisp in the oven.
- Whisk the milk in gradually to avoid lumps, and keep the sauce at a gentle simmer so it thickens without catching on the base.
Substitutions
- Replace Cremini mushrooms with Button mushrooms for a milder mushroom flavour.
- Replace Whole milk with Low-fat milk for a lighter sauce, but simmer it a little longer to thicken.
Storage
- Refrigerate up to 3 days
- Cool, cover and refrigerate. Reheat in a 180°C (355°F) oven for 15 to 20 minutes until piping hot; add a fresh sprinkle of Fried onion for the best crunch.
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Recipe overview
- Servings: 4 servings
- Total time: 50min (20min active)
- Difficulty: Easy
- Cuisine: American
-
Allergens:
Gluten Milk Wheat
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