Creamy Green Bean and Mushroom Casserole with Crispy Onions Recipe

Introduction

This classic green bean casserole is a comforting blend of tender green beans, savory mushrooms, and a rich creamy sauce topped with crispy onions. Perfect as a hearty side dish for family dinners or holiday meals.

Ingredients

• 4 tbsp butter
• 2 tbsp olive oil
• 2¾ cups sliced cremini or button mushrooms
• 1 lb 2 oz green beans, trimmed
• 6½ tbsp all-purpose flour
• 1¾ cups whole milk
• 1-2 cups crispy onions

Instructions

1. Step 1: Heat 1 tablespoon of butter and the olive oil in a large pan over medium heat. Add the sliced mushrooms and fry for 10 to 15 minutes until golden brown.
2. Step 2: Stir in the trimmed green beans and cook for another 3 to 4 minutes until the beans turn bright green. Remove the vegetables from the pan and set aside on a plate.
3. Step 3: Preheat the oven to 400°F (gas mark 6). In the same pan, melt the remaining butter until foaming. Remove the pan from the heat briefly and sprinkle over the flour, stirring to form a golden brown paste.
4. Step 4: Return the pan to the heat and gradually add the milk a splash at a time, stirring constantly until a smooth, thick white sauce forms. Season the sauce to taste with salt and pepper.
5. Step 5: Stir the cooked green beans and mushrooms into the white sauce, then transfer the mixture to a medium ovenproof dish.
6. Step 6: Scatter the crispy onions evenly on top. Bake for 20 to 30 minutes until the casserole is bubbling and golden on top. Cover the dish if the onions brown too quickly.

Tips & Variations

• For extra flavor, add a splash of soy sauce or Worcestershire sauce to the white sauce before combining with the vegetables.
• Use fresh green beans for the best texture, but frozen can be substituted—just thaw and drain before cooking.
• Try topping with shredded cheddar cheese along with crispy onions for a richer twist.

Storage

Store leftover casserole in an airtight container in the refrigerator for up to 3 days. To reheat, cover with foil and warm in a 350°F oven until heated through, about 15-20 minutes. Avoid microwaving to keep the onions crispy.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I make green bean casserole ahead of time?

Yes, you can prepare the casserole and refrigerate it unbaked for up to 24 hours. Add the crispy onions just before baking to keep them crisp.

What can I use instead of crispy onions?

If you don’t have crispy onions, substitute fried shallots, toasted breadcrumbs, or crushed fried onions for a similar crunchy topping.

Creamy Green Bean and Mushroom Casserole with Crispy Onions Recipe

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★★★★★

4.8 from 646 reviews

• Author: Jake
• Total Time: 1 hour
• Yield: 6 servings 1x

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Description

A classic creamy green bean casserole featuring sautéed mushrooms and fresh green beans in a smooth white sauce, topped with crispy fried onions and baked to golden perfection. This comforting side dish combines rich flavors and textures perfect for holiday dinners or family meals.

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Ingredients

Scale 1x2x3x

Vegetables

• 1 lb 2 oz green beans, trimmed
• 2¾ cups sliced cremini or button mushrooms

Fats and Oils

• 4 tbsp butter
• 2 tbsp olive oil

Thickening and Liquid

• 6½ tbsp all-purpose flour
• 1¾ cups whole milk

Toppings

• 1–2 cups crispy onions

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Instructions

1. Sauté Mushrooms and Green Beans: Heat 1 tablespoon of butter and all the olive oil in a large pan over medium heat. Add the sliced mushrooms and fry them for 10 to 15 minutes until they turn golden brown. Stir in the trimmed green beans and continue cooking for another 3 to 4 minutes until the beans brighten in color. Once cooked, transfer the vegetables to a plate and set aside.
2. Make the White Sauce: Preheat the oven to 400°F (gas mark 6). In the same pan, melt the remaining 3 tablespoons of butter over medium heat until it foams. Remove the pan briefly from the heat and sprinkle the all-purpose flour over the melted butter. Stir briskly to form a golden brown paste (roux). Return the pan to the heat and gradually add the whole milk, pouring it in a splash at a time while continuously stirring to achieve a smooth, thick white sauce. Season well with salt and pepper to taste.
3. Combine and Assemble: Stir the sautéed mushrooms and green beans into the prepared white sauce, mixing thoroughly. Spoon the mixture into a medium-sized ovenproof dish, spreading it evenly.
4. Add Crispy Onions and Bake: Scatter 1 to 2 cups of crispy fried onions evenly over the top of the casserole. Place the dish in the preheated oven and bake for 20 to 30 minutes until the sauce is bubbling and the onions have turned golden brown. If the onions brown too quickly, cover the casserole loosely with foil to prevent burning.

Notes

• For a richer flavor, use cremini mushrooms instead of button mushrooms.
• Trim and wash green beans thoroughly for the best texture and color.
• Adjust the amount of crispy onions according to your preference for crunchiness.
• To make ahead, prepare the casserole up to the baking stage, cover, and refrigerate. Bake just before serving, adding extra time if cold from the fridge.
• To make it gluten-free, substitute all-purpose flour with a gluten-free flour blend.

• Prep Time: 15 minutes
• Cook Time: 45 minutes
• Category: Casserole
• Method: Baking
• Cuisine: American

Keywords: green bean casserole, mushroom casserole, holiday side dish, creamy casserole, crispy onion topping