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Fresh Green Bean Casserole from Scratch

Fresh green bean casserole from scratch combines crisp-tender green beans and a creamy mushroom sauce with homemade crispy onions. The casserole bakes until bubbling around the edges, then gets a final five minutes in the oven with the golden onion topping.
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Prep Time 20 minutes
Cook Time 45 minutes
soaking and resting 20 minutes
Total Time 1 hour 25 minutes
Servings: 6 servings
Course: Side Dish
Cuisine: American
Calories: 340
Ingredients Equipment Method Notes

Ingredients
  

For the crispy onions
  • 2 cup vegetable oil for frying
  • 1 yellow onion large, about 12 ounces, thinly sliced into rings
  • 0.5 cup buttermilk
  • 0.5 cup cornstarch
For the casserole
  • 3 qt water
  • 1.5 lb fresh green beans trimmed and cut into 2-inch pieces
  • 4 tbsp butter unsalted, divided
  • 8 oz cremini mushrooms sliced
  • 2 cloves garlic minced
  • 0.25 cup all-purpose flour
  • 1 cup chicken broth low-sodium
  • 1 cup whole milk
  • 1 tsp kosher salt
  • 0.25 tsp black pepper

Equipment

  • 1 10-inch skillet
  • 1 rimmed baking sheet
  • 1 6-quart pot
  • 1 9x13-inch baking dish
  • 1 12-inch skillet

Method
 

Make the crispy onions
  1. Heat the vegetable oil in a 10-inch skillet over medium heat to 350°F.
  2. Line a rimmed baking sheet with paper towels.
  3. Separate the onion rings and soak them in the buttermilk for 10 minutes.
  4. Lift the onion rings from the buttermilk in small batches, let excess buttermilk drip off, then toss them in the cornstarch to coat and shake off the excess.
  5. Fry the onion rings in batches for 2 to 3 minutes, turning once, until golden and crisp; drain them on the paper towels.
Make and bake the casserole
  1. Preheat the oven to 375°F.
  2. Bring the water to a boil in a 6-quart pot.
  3. Add the green beans and boil for 3 minutes, until bright green and crisp-tender; drain well and spread them on a clean kitchen towel.
  4. Grease a 9x13-inch baking dish with 1 tablespoon of the butter.
  5. Melt the remaining 3 tablespoons butter in a 12-inch skillet over medium heat, add the mushrooms, and cook for 6 to 8 minutes, stirring occasionally, until browned and their released liquid has evaporated.
  6. Add the garlic and cook for 30 seconds.
  7. Sprinkle in the flour and cook for 1 minute, stirring.
  8. Gradually whisk in the chicken broth and milk, bring the sauce to a simmer, and cook for 2 to 3 minutes, whisking, until thickened.
  9. Stir in the salt and pepper, fold in the green beans, and transfer the mixture to the prepared baking dish.
  10. Bake for 20 to 25 minutes, until the sauce is bubbling around the edges.
  11. Scatter the crispy onions evenly over the casserole and bake for 5 minutes.
  12. Rest the casserole for 10 minutes before serving.

Notes

Dry the green beans well after draining so excess water does not thin the sauce. Refrigerate leftovers for 3 to 4 days; freezing is not recommended because the sauce and green beans can lose their texture. For a vegetarian version, use vegetable broth instead of chicken broth.