Go Back

Classic Christmas Green Bean Casserole with Crispy Onions

Print Recipe Pin Recipe
Prep Time 20 minutes
Cook Time 30 minutes
Total Time 50 minutes
Course Side Dish
Cuisine American
Servings 8

Equipment

  • Large pot To blanch the green beans. A Dutch oven or deep saucepan works perfectly.
  • Large skillet For sautéing mushrooms and making the sauce.
  • Whisk To combine the sauce ingredients smoothly.
  • Strainer or colander For draining green beans after blanching.
  • 9x13-inch baking dish Ideal for evenly spreading out the casserole. You can use a ceramic or glass dish.
  • Mixing spoon or spatula For stirring and spreading ingredients.

Ingredients
  

For the Green Beans

  • 1 ½ pounds fresh green beans trimmed and cut into 2-inch pieces
  • Salt for blanching

For the Mushroom Sauce

  • 2 tablespoons unsalted butter
  • 1 tablespoon olive oil
  • 1 small yellow onion finely chopped
  • 8 ounces cremini mushrooms sliced
  • 2 garlic cloves minced
  • 2 tablespoons all-purpose flour
  • ¾ cup low-sodium chicken broth or vegetable broth for a vegetarian option
  • 1 cup heavy cream
  • ½ teaspoon ground black pepper
  • ½ teaspoon salt
  • ¼ teaspoon ground nutmeg optional, but adds holiday warmth

For the Topping

  • 1 ½ cups store-bought crispy fried onions like French’s
  • Optional: ½ cup grated parmesan for extra richness

Instructions
 

Blanch the Green Beans

  1. Bring a large pot of salted water to a boil. Add the trimmed green beans and cook for 3–4 minutes, just until tender but still crisp. Drain and immediately transfer them to a bowl of ice water to stop the cooking process. Once cooled, drain and set aside.

Make the Mushroom Sauce

  1. In a large skillet, melt the butter with olive oil over medium heat. Add the chopped onion and sauté for 3–4 minutes until softened. Stir in the sliced mushrooms and cook for another 5–6 minutes, until mushrooms are browned and any liquid has evaporated. Add the minced garlic and cook for another minute.
  2. Sprinkle the flour over the mushroom mixture and stir to coat evenly. Cook for 1 minute, stirring constantly. Gradually whisk in the chicken broth and then the heavy cream. Bring to a simmer and cook until the sauce thickens, about 3–4 minutes. Season with salt, pepper, and nutmeg, if using.

Combine Beans and Sauce

  1. Preheat your oven to 375°F (190°C). In a large mixing bowl, combine the blanched green beans with the mushroom sauce. Stir until the green beans are evenly coated.

Assemble the Casserole

  1. Transfer the green bean mixture into a 9x13-inch baking dish and spread it out evenly. Top with the crispy fried onions. If you’re feeling a little indulgent, sprinkle grated parmesan on top for an extra savory bite.

Bake

  1. Place the casserole in the preheated oven and bake uncovered for 25–30 minutes, or until the sauce is bubbling and the onions are golden and crispy.

Serve

  1. Remove from the oven and let sit for 5 minutes before serving. This gives the casserole time to settle and makes it easier to scoop. Serve warm and watch it disappear quickly from the holiday table.