Old-School Green Bean Casserole

Featured in: Everyday Comforts

This nostalgic dish highlights tender green beans nestled in a creamy mushroom sauce, topped with crispy fried onions for texture and flavor. Fresh or thawed green beans are briefly boiled and combined with a rich mixture of butter, sautéed mushrooms, onions, garlic, and a silky sauce made from milk, cream, and vegetable broth. The casserole bakes until bubbling and golden, offering a comforting, savory side that pairs perfectly with festive dinners. Optional nutmeg and sharp cheddar add warmth and depth. Easy to prepare and beloved by many.

Updated on Tue, 11 Nov 2025 08:11:00 GMT
Creamy Old-School Green Bean Casserole with golden crispy onions, a comforting Thanksgiving side. Save
Creamy Old-School Green Bean Casserole with golden crispy onions, a comforting Thanksgiving side. | butterhollow.com

A nostalgic, creamy side dish featuring tender green beans, savory mushrooms, and crispy fried onions—a classic for holiday feasts and family dinners.

This green bean casserole was always on my family&s holiday table. I remember helping my grandmother trim the beans and watching the onions turn golden in the oven. It&s a dish that brings everyone together, whether for Thanksgiving or a regular Sunday dinner.

Ingredients

  • Fresh Green Beans: 900 g (2 lb), trimmed and cut into 5 cm (2-inch) pieces (or 900 g frozen cut green beans, thawed and drained)
  • Unsalted Butter: 2 tbsp
  • Cremini or Button Mushrooms: 250 g (9 oz), sliced
  • Yellow Onion: 1 small, finely chopped
  • Garlic: 2 cloves, minced
  • All-Purpose Flour: 2 tbsp
  • Whole Milk: 240 ml (1 cup)
  • Heavy Cream: 120 ml (half cup)
  • Low-Sodium Vegetable Broth: 120 ml (half cup)
  • Salt: 1 tsp
  • Black Pepper: half tsp
  • Ground Nutmeg (optional): half tsp
  • Crispy Fried Onions: 150 g (1.5 cups), store-bought or homemade

Instructions

Preheat Oven:
Preheat the oven to 180°C (350°F).
Cook Green Beans:
Bring a large pot of salted water to a boil. Add green beans and cook for 5 minutes until just tender but still bright green. Drain and immediately rinse under cold water to stop cooking. Set aside.
Make Mushroom Sauce:
In a large skillet over medium heat, melt the butter. Add mushrooms and cook for 5-6 minutes until tender and browned. Add onion and garlic, cooking for another 2-3 minutes until softened.
Thicken Sauce:
Stir in the flour and cook for 1 minute, stirring constantly. Gradually whisk in milk, cream, and broth. Bring to a simmer and cook until thickened, about 5 minutes. Season with salt, pepper, and nutmeg (if using).
Combine Beans and Sauce:
Add the drained green beans to the skillet and toss to coat evenly in the sauce.
Transfer and Top:
Transfer the mixture to a 2-liter (2-quart) baking dish. Sprinkle half of the crispy fried onions on top.
Bake:
Bake for 25 minutes until bubbling. Remove from oven, top with remaining onions, and bake for 5-7 minutes more until golden and crisp.
Serve:
Let cool for 5 minutes before serving.
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| butterhollow.com

One year, the kids insisted on adding extra crispy onions, and it turned out even tastier. Now, we make it together every Thanksgiving, with everyone sprinkling their own onion layer before baking.

Make Ahead Tips

Assemble the casserole through step six, cover, and refrigerate for up to 24 hours. Top with onions just before baking for optimal texture.

Add Cheese for Depth

For a richer flavor, stir 50 g of grated sharp cheddar or Gruyère into the sauce before combining with the beans.

Serving Suggestions

This side pairs perfectly with roast turkey, chicken, or even vegetarian mains for a complete festive meal.

This homemade Old-School Green Bean Casserole features a rich mushroom sauce, perfect comfort food. Save
This homemade Old-School Green Bean Casserole features a rich mushroom sauce, perfect comfort food. | butterhollow.com

This old-school casserole always disappears quickly at the table. Its comforting flavors and easy prep make it a side you&ll come back to every holiday.

Kitchen Tips & Answers

What type of green beans work best?

Fresh trimmed green beans are ideal, but frozen, thawed, and drained beans work well as a convenient substitute.

Can I use different mushrooms?

Yes, cremini or button mushrooms are recommended for a mild, savory flavor, but other varieties can be used depending on preference.

How do you achieve the crispy topping?

Crispy fried onions, either store-bought or homemade, are layered on top and baked to golden perfection for a crunchy finish.

Is there a way to prepare this ahead of time?

The casserole can be assembled through step 6 and refrigerated for up to 24 hours. Add onions and bake just before serving.

What flavors complement this dish well?

Adding sharp cheddar or Gruyère enriches the sauce, while it pairs beautifully with roast poultry for a complete meal.

Old-School Green Bean Casserole

Creamy green beans with mushrooms and crispy onions for a classic holiday side.

Prep duration
15 min
Heat duration
35 min
Complete duration
50 min
Created by Ella Thompson


Skill level Easy

Heritage American

Output 6 Portions

Eating preferences Meat-free

What you'll need

Vegetables

01 2 lb fresh green beans, trimmed and cut into 2-inch pieces (or frozen cut green beans, thawed and drained)

Sauce Base

01 2 tbsp unsalted butter
02 9 oz cremini or button mushrooms, sliced
03 1 small yellow onion, finely chopped
04 2 garlic cloves, minced
05 2 tbsp all-purpose flour
06 1 cup whole milk
07 ½ cup heavy cream
08 ½ cup low-sodium vegetable broth
09 1 tsp salt
10 ½ tsp black pepper
11 ½ tsp ground nutmeg (optional)

Topping

01 1½ cups crispy fried onions (store-bought or homemade)

Method

Phase 01

Preheat oven: Set oven temperature to 350°F (180°C).

Phase 02

Blanch green beans: Boil a large pot of salted water. Add green beans and cook for 5 minutes until tender-crisp and bright green. Drain and rinse under cold water to stop cooking. Set aside.

Phase 03

Sauté mushrooms, onion, and garlic: Melt butter in a large skillet over medium heat. Add mushrooms and cook for 5 to 6 minutes until browned and tender. Add onion and garlic; cook 2 to 3 minutes until softened.

Phase 04

Make sauce: Stir in flour and cook 1 minute, stirring continuously. Gradually whisk in milk, heavy cream, and vegetable broth. Simmer for 5 minutes until thickened. Season with salt, pepper, and nutmeg if using.

Phase 05

Combine green beans with sauce: Add the drained green beans to the skillet and toss thoroughly to coat with the sauce.

Phase 06

Assemble casserole: Transfer mixture into a 2-quart baking dish. Evenly sprinkle half of the crispy fried onions over the top.

Phase 07

Bake first layer: Bake uncovered for 25 minutes until the sauce is bubbling.

Phase 08

Add topping and finish baking: Remove from oven, add remaining crispy fried onions on top, and bake for an additional 5 to 7 minutes until golden and crisp.

Phase 09

Rest before serving: Allow to cool for 5 minutes before serving.

Kitchen tools needed

  • Large pot
  • Colander
  • Large skillet
  • Whisk
  • 2-quart baking dish
  • Oven

Allergy details

Always review individual ingredients for potential allergens and seek professional medical guidance if uncertain.
  • Contains milk (dairy), wheat (gluten in flour and fried onions), and soy (possible in store-bought fried onions). Verify labels for allergens.

Nutrient breakdown per portion

Numbers shown are estimates only - consult healthcare providers for specific advice.
  • Energy: 265
  • Fats: 15 g
  • Carbohydrates: 25 g
  • Proteins: 6 g