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Best Ever Green Bean Casserole

This recipe for Alton Brown's Green Bean Casserole features homemade crispy baked onions, perfectly blanched green beans, and a rich, savory mushroom cream sauce. The components are expertly combined and baked until bubbly, creating a fresh, elevated take on a classic holiday dish.
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 for blanching
  • 1 Colander
  • 1 12-inch cast iron skillet oven-safe

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

1. For truly crispy onions, ensure they are thinly and evenly sliced. Tossing them frequently during baking promotes uniform browning and crispness. If they start to burn, lower the oven temperature slightly. 2. The ice bath for green beans is crucial to halt cooking and preserve their vibrant color and crisp-tender texture. Do not skip this step. 3. When cooking the mushroom sauce, allow the mushrooms to release their liquid fully before adding the flour; this deepens their flavor. Use freshly ground nutmeg for superior aroma. 4. Serve immediately to maintain the casserole's warmth and the onions' crispness.