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Green Bean Casserole With Garlic Butter - Cozy, Flavorful, and Crowd-Pleasing

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Prep Time 15 minutes
Cook Time 35 minutes
Total Time 50 minutes
Servings: 8 servings
Ingredients Method

Ingredients
  

  • Fresh green beans: About 1 1/2 pounds, ends trimmed and cut in half.
  • Unsalted butter: 5 tablespoons, divided.
  • Garlic: 4 cloves, finely minced.
  • Yellow onion: 1 small, finely chopped.
  • Cremini or button mushrooms: 8 ounces, sliced.
  • All-purpose flour: 3 tablespoons.
  • Chicken or vegetable broth: 1 1/4 cups, low-sodium.
  • Half-and-half or whole milk: 3/4 cup.
  • Parmesan cheese: 1/3 cup, finely grated (optional but recommended).
  • Nutmeg: A small pinch.
  • Kosher salt and black pepper: To taste.
  • Crispy fried onions: 1 1/2 cups (store-bought or homemade).
  • Panko breadcrumbs: 1/2 cup.
  • Olive oil: 1 tablespoon (for the topping).
  • Lemon zest: 1/2 teaspoon (optional, for brightness).

Method
 

  1. Heat the oven: Preheat to 375°F (190°C). Grease a 9x13-inch baking dish or similar casserole pan.
  2. Blanch the green beans: Bring a large pot of salted water to a boil. Add the beans and cook for 3–4 minutes until bright green and just tender. Drain and plunge into ice water to stop the cooking. Pat dry.
  3. Make the garlic butter base: In a large skillet, melt 3 tablespoons butter over medium heat. Add the onion and cook until soft, about 3–4 minutes. Stir in the garlic and cook 30 seconds until fragrant.
  4. Sauté the mushrooms: Add the mushrooms and a pinch of salt. Cook, stirring occasionally, until they release their moisture and brown slightly, 6–8 minutes.
  5. Create the sauce: Sprinkle the flour over the mushrooms and stir for 1 minute to coat. Slowly whisk in the broth, then the half-and-half. Simmer 3–5 minutes, stirring, until the sauce thickens enough to coat a spoon.
  6. Season the sauce: Add the nutmeg, pepper, and 1/2 teaspoon salt to start. Stir in the Parmesan, if using, until melted. Taste and adjust seasoning. The sauce should taste slightly salty—remember the beans and topping will mellow it out.
  7. Combine with beans: Add the blanched green beans to the skillet and toss to coat evenly. Transfer the mixture to the prepared baking dish.
  8. Make the crunchy topping: In a small bowl, melt the remaining 2 tablespoons butter. Stir in the panko, olive oil, and lemon zest. Fold in the crispy onions. Season with a pinch of salt and pepper.
  9. Top and bake: Scatter the topping evenly over the casserole. Bake 18–22 minutes, until bubbling at the edges and golden on top.
  10. Rest and serve: Let it sit for 5–10 minutes to set slightly. Serve warm.