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From Scratch Green Bean Casserole

From scratch green bean casserole combines crisp-tender green beans and browned mushrooms in a creamy sauce, baked beneath freshly fried onions. The golden, crisp onion topping makes this homemade version a standout side dish.
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Prep Time 20 minutes
Cook Time 50 minutes
Soaking time 10 minutes
Total Time 1 hour 20 minutes
Servings: 8 servings
Course: Side Dish
Cuisine: American
Calories: 350
Ingredients Equipment Method Notes

Ingredients
  

For the casserole
  • cooking spray
  • 4 qt water
  • 2 lb fresh green beans trimmed
  • 4 tbsp unsalted butter
  • 1 lb cremini mushrooms sliced
  • 2 cloves garlic minced
  • 1.5 cup low-sodium chicken broth
  • 1 cup heavy cream
  • 2 tbsp cornstarch
  • 1 tsp kosher salt
  • 0.5 tsp black pepper
For the crispy onions
  • 1 yellow onion medium, thinly sliced
  • 1 cup buttermilk
  • 0.5 cup all-purpose flour
  • 2 cup canola oil for frying

Equipment

  • 1 9x13-inch baking dish
  • 1 12-inch skillet
  • 1 8-inch saucepan

Method
 

Prepare the casserole
  1. Preheat the oven to 375°F and coat a 9x13-inch baking dish with cooking spray.
  2. Bring the 4 quarts of water to a boil in a large pot, add the green beans, and cook for 4–5 minutes until bright green and crisp-tender; drain well.
  3. Melt the butter in a 12-inch skillet over medium-high heat, add the mushrooms and garlic, and cook for 8–10 minutes, stirring occasionally, until browned and their liquid has evaporated.
  4. Reserve 2 tablespoons of the broth, then add the remaining broth and the cream to the skillet; bring to a simmer.
  5. Whisk the cornstarch into the reserved broth until smooth, stir it into the skillet with the salt and pepper, and simmer for 1–2 minutes until the sauce thickens.
  6. Fold the green beans into the sauce, transfer the mixture to the prepared baking dish, and bake for 20–25 minutes until bubbling around the edges.
Fry the onions and finish
  1. While the casserole bakes, soak the sliced onion in the buttermilk for 10 minutes.
  2. Heat the canola oil in an 8-inch saucepan over medium heat to 350°F, checking the temperature with a thermometer.
  3. Lift the onion slices from the buttermilk, let the excess drip off, and toss them in the flour until lightly coated.
  4. Fry the onions in batches for 2–3 minutes per batch until golden, then drain on paper towels.
  5. Scatter the fried onions over the casserole and bake for 5 minutes until the topping is crisp and golden.

Notes

For the crispiest topping, fry the onions in batches so the oil temperature stays steady. Refrigerate leftovers for 3–4 days; freezing is not recommended because the fried onions lose their crispness. For a gluten-free option, use a gluten-free all-purpose flour blend.