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Best Ever Green Bean Casserole

This recipe from Alton Brown elevates the classic green bean casserole by featuring homemade crispy baked onions and a rich, from-scratch mushroom cream sauce. Fresh green beans are perfectly blanched to retain their vibrant color and tender bite. All components are combined and baked until bubbly, creating a deeply flavorful and textured side dish that's a delightful alternative to traditional versions.
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Prep Time 25 minutes
Cook Time 45 minutes
Total Time 1 hour 10 minutes
Course lunch/dinner
Cuisine American
Servings 4 people
Calories 814.1 kcal

Equipment

  • 1 Sheet Pan
  • 1 Large Mixing Bowl
  • 1 8-quart saucepan
  • 1 Colander
  • 1 12-inch cast iron skillet Or an equivalent oven-safe casserole dish

Ingredients
  

Main

  • 2 medium onions thinly sliced
  • 1/4 cup all-purpose flour
  • 2 tablespoons panko bread crumbs
  • 1 teaspoon kosher salt
  • Nonstick cooking spray
  • 2 tablespoons plus 1 teaspoon kosher salt divided
  • 1 pound fresh green beans rinsed, trimmed and halved
  • 2 tablespoons unsalted butter
  • 12 ounces mushrooms trimmed and cut into 1/2-inch pieces
  • 1/2 teaspoon freshly ground black pepper
  • 2 cloves garlic minced
  • 1/4 teaspoon freshly ground nutmeg
  • 2 tablespoons all-purpose flour
  • 1 cup chicken broth
  • 1 cup half-and-half

Instructions
 

  • Preheat the oven to 475 degrees F.
  • Combine the onions, flour, panko and salt in a large mixing bowl and toss to combine. Coat a sheet pan with nonstick cooking spray and evenly spread the onions on the pan. Place the pan on the middle rack of the oven and bake until golden brown, approximately 30 minutes. Toss the onions 2 to 3 times during cooking. Once done, remove from the oven and set aside until ready to use. Turn the oven down to 400 degrees F.
  • While the onions are cooking, prepare the beans. Bring a gallon of water and 2 tablespoons of salt to a boil in an 8-quart saucepan. Add the beans and blanch for 5 minutes. Drain in a colander and immediately plunge the beans into a large bowl of ice water to stop the cooking. Drain and set aside.
  • Melt the butter in a 12-inch cast iron skillet set over medium-high heat. Add the mushrooms, 1 teaspoon salt and pepper and cook, stirring occasionally, until the mushrooms begin to give up some of their liquid, approximately 4 to 5 minutes. Add the garlic and nutmeg and continue to cook for another 1 to 2 minutes. Sprinkle the flour over the mixture and stir to combine. Cook for 1 minute. Add the broth and simmer for 1 minute. Decrease the heat to medium-low and add the half-and-half. Cook until the mixture thickens, stirring occasionally, approximately 6 to 8 minutes.
  • Remove from the heat and stir in 1/4 of the onions and all of the green beans. Top with the remaining onions. Place into the oven and bake until bubbly, approximately 15 minutes. Remove and serve immediately.

Notes

Achieving truly crispy onions is key; ensure they are spread thinly and tossed frequently during baking to promote even browning without burning. The ice bath for the green beans is crucial for preserving their vibrant color and crisp-tender texture, preventing overcooking. When making the mushroom sauce, cook the mushrooms until their liquid has almost entirely evaporated to concentrate their flavor. Whisk the flour thoroughly to prevent lumps, creating a smooth, luscious sauce. For an elevated touch, consider adding a splash of dry sherry or white wine when deglazing the mushrooms for deeper umami. Fresh thyme or a pinch of sage in the sauce can also complement the flavors beautifully.