Green Bean Casserole With Crispy Onions (From Scratch)
An inspired take on a classic American side dish, this Green Bean Casserole with Crispy Onions offers a comforting blend of fresh green beans, creamy sauce, and a crunchy onion topping. Ideal for holiday feasts and family gatherings, this dish captures the essence of tradition while ensuring a vibrant freshness that elevates its flavorful profile.
Equipment
- Large pot (for blanching)
- Large bowl (for ice bath)
- 10-inch skillet or sauté pan
- Whisk
- 2-quart casserole dish or 9x13 inch (23x33cm) baking dish
- Instant-read thermometer (optional)
Ingredients
- 1.1 lb fresh green beans trimmed and halved, about 500g
- 2 tablespoons unsalted butter 28g
- 4 oz button mushrooms thinly sliced, about 1 cup / 115g
- 1 clove garlic minced
- 2 tablespoons all-purpose flour 16g
- 1 cup whole milk 240ml
- ½ cup heavy cream 120ml
- ½ teaspoon sea salt
- ¼ teaspoon black pepper freshly ground
- 1 ½ cups crispy fried onions store-bought or homemade, about 85g / 3oz
- 3 qt ice water for ice bath
- 1 teaspoon cooking spray or butter for greasing the casserole dish
Instructions
- Preheat your oven to 190°C (375°F) and bring a large pot of salted water to a boil.
- Blanch the green beans in the boiling water for 4-5 minutes, until they are bright green and tender-crisp. Immediately transfer them to a bowl of ice water to stop the cooking process, then drain.1.1 lb fresh green beans, 3 qt ice water
- In a large skillet over medium heat, melt the butter. Sauté the mushrooms until golden brown and they have released their moisture, about 5-7 minutes. Add the garlic and cook for 30 seconds until fragrant.2 tablespoons unsalted butter, 4 oz button mushrooms, 1 clove garlic
- Sprinkle the flour over the mushrooms and cook, stirring constantly, for 1 minute to form a roux.2 tablespoons all-purpose flour
- Gradually whisk in the milk and cream, a little at a time, stirring constantly. Bring to a gentle simmer and cook for 3-4 minutes, whisking frequently, until the sauce thickens enough to coat the back of a spoon. Season with salt and pepper.1 cup whole milk, 1/2 cup heavy cream, 1/2 teaspoon sea salt, 1/4 teaspoon black pepper
- Add the blanched green beans to the skillet and toss to coat them in the creamy mushroom sauce.1.1 lb fresh green beans
- Transfer the green bean mixture to a lightly greased 2-quart casserole dish or 9x13 inch (23x33cm) baking dish. Scatter the crispy fried onions over the top.1 teaspoon cooking spray or butter, 1 1/2 cups crispy fried onions
- Bake in the preheated oven for 25-30 minutes, until the top is golden and the casserole is bubbling.
Notes
Storage: Refrigerate leftovers in an airtight container for up to 4 days. Reheat covered with foil at 175°C / 350°F for 15 minutes, or microwave individual servings on medium power in 90-second bursts.
Freezer-friendly: Freeze without the onion topping in portions for up to 2 months. Thaw overnight in the fridge, reheat in the oven, and add fresh crispy onions before serving.
Make-ahead: Assemble the full casserole (without onion topping), cover tightly, and refrigerate for up to 24 hours. Add onions before baking and add 5 extra minutes to the bake time.
Substitution: For a richer flavour, swap button mushrooms for a mix of cremini and shiitake. For dairy-free, use oat milk and vegan butter — the sauce will be slightly thinner but still coats the beans well.
Pro tip: Cook the roux for a full 60 seconds before adding any liquid — this eliminates the raw flour taste and gives the sauce a smooth, stable body that won't break in the oven.
Nutrition
Serving: 1servingCalories: 259kcalCarbohydrates: 17gProtein: 4gFat: 20gSaturated Fat: 11gPolyunsaturated Fat: 1gMonounsaturated Fat: 4gTrans Fat: 0.2gCholesterol: 37mgSodium: 362mgPotassium: 322mgFiber: 3gSugar: 6gVitamin A: 1048IUVitamin C: 11mgCalcium: 112mgIron: 1mg
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