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The Only Green Bean Casserole You’ll Ever Need This Thanksgiving

Print Recipe
Prep Time 25 minutes
Cook Time 40 minutes
Total Time 1 hour 5 minutes
Servings: 8 people
Course: Side Dish
Cuisine: American
Calories: 290
Ingredients Method Notes

Ingredients
  

For the Green Beans:
  • 2 pounds fresh green beans trimmed and cut into 1½-inch pieces
  • Salt for blanching water
For the Mushroom Sauce:
  • 4 tablespoons unsalted butter
  • 1 medium yellow onion finely diced
  • 10 ounces cremini or button mushrooms chopped
  • 3 cloves garlic minced
  • ¼ cup all-purpose flour
  • 1 ½ cups chicken or vegetable broth
  • 1 ¼ cups heavy cream
  • 1 teaspoon soy sauce secret depth booster!
  • ½ teaspoon black pepper
  • ½ teaspoon salt adjust to taste
  • ¼ teaspoon nutmeg optional but delicious
For the Topping:
  • 2 cups crispy fried onions store-bought or homemade

Method
 

Prep the Green Beans
  1. Bring a large pot of heavily salted water to a boil. Add the green beans and blanch for 4–5 minutes, just until they turn bright green and slightly tender. Immediately transfer them into a bowl of ice water to stop the cooking.
  2. Blanching keeps your casserole from turning limp and colorless. This step alone makes it taste restaurant-worthy instead of cafeteria-style.
Make the Creamy Mushroom Sauce
  1. In a large skillet or Dutch oven, melt the butter over medium heat. Add the diced onion and sauté for 3–4 minutes until softened. Add the mushrooms and cook until they release their moisture and begin to brown, about 6–7 minutes.
  2. Stir in the garlic and cook for 30 seconds more.
  3. Sprinkle the flour over the vegetables and stir to coat; this forms your roux. Cook for 1 minute to get rid of the raw flour taste.
  4. Slowly whisk in the broth until no lumps remain, then add the heavy cream. Season with salt, pepper, soy sauce, and nutmeg. Let the mixture simmer gently for 4–5 minutes, until thickened to a gravy-like consistency.
  5. Taste and adjust seasoning. This sauce should be so good you’d happily spoon it over mashed potatoes.
Combine the Sauce and Beans
  1. Drain the green beans well and pat dry. Add them to the mushroom sauce and fold gently until everything is evenly coated.
Assemble and Bake
  1. Preheat your oven to 375°F (190°C).
  2. Transfer the green bean mixture into a 9×13-inch baking dish. Bake for 20 minutes uncovered, until the sauce is bubbling around the edges.
Add the Crispy Topping
  1. Remove the dish from the oven, scatter the fried onions evenly over the top, and return it to the oven for another 10 minutes. The onions will turn beautifully golden and extra crunchy.
  2. Let the casserole rest for 5 minutes before serving.

Notes

Make Ahead Option:
You can prepare the entire casserole—minus the crispy onion topping—the day before. Store it in the fridge, covered. On Thanksgiving Day, bake it for 25 minutes, add the onions, and bake the final 10 minutes.
Add a Cheese Twist:
If your family loves cheese, stir ½ cup shredded Parmesan or Gruyère into the mushroom sauce. It adds an elegant depth without overpowering the dish.
Gluten-Free Version:
Use a gluten-free flour blend in the roux.
Choose gluten-free crispy onions (several brands make them now).
Vegan Version:
Swap butter for vegan butter, heavy cream for unsweetened almond milk plus 2 tablespoons cashew cream, and use vegetable broth. Many grocery stores now carry vegan crispy onions, too.