Old-School Green Bean Casserole

Featured in: Comfort Baking

This nostalgic side features tender green beans coated in a creamy sauce made with mushrooms, butter, and cream. Cooked to perfection and topped with crispy fried onions, it brings a perfect balance of textures and flavors to any holiday or family meal. Preparation is quick and easy, making it an ideal comforting dish to complement your main courses.

Updated on Sat, 15 Nov 2025 09:02:00 GMT
Creamy Old-School Green Bean Casserole with golden fried onions, a comforting holiday classic dish. Save
Creamy Old-School Green Bean Casserole with golden fried onions, a comforting holiday classic dish. | butterhearth.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 casserole reminds me of family gatherings where everyone eagerly anticipated this dish at the table—it's always been a comfort food favorite for us.

Ingredients

  • Green beans: 900 g (2 lb) fresh, trimmed and cut into 5 cm (2-inch) pieces or 900 g frozen, 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 (½ cup)
  • Low-sodium vegetable broth: 120 ml (½ cup)
  • Salt: 1 tsp
  • Black pepper: ½ tsp
  • Ground nutmeg (optional): ½ tsp
  • Crispy fried onions: 150 g (1½ cups), store-bought or homemade

Instructions

Preheat oven:
Preheat the oven to 180°C (350°F)
Blanch 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 rinse under cold water.
Prepare vegetables:
In a large skillet over medium heat, melt butter. Add mushrooms and cook for 5-6 minutes until tender and browned. Add onion and garlic, cooking for 2-3 minutes until softened.
Make the sauce:
Stir in flour and cook for 1 minute, stirring constantly. Gradually whisk in milk, cream, and broth. Simmer until thickened, about 5 minutes. Season with salt, pepper, and nutmeg.
Combine:
Add drained green beans to the skillet. Toss to coat in sauce.
Transfer and top:
Transfer 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 until golden and crisp.
Rest:
Let cool for 5 minutes before serving.
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When we make this for Thanksgiving, everyone races to get the biggest helping—it's always the first dish to disappear at our family table.

Required Tools

Large pot, colander, large skillet, whisk, 2-liter (2-quart) baking dish, oven

Nutritional Information

Per serving: Calories 265, Total Fat 15 g, Carbohydrates 25 g, Protein 6 g

Notes

For extra flavor, add 50 g grated sharp cheddar or Gruyère cheese to the sauce. To make ahead, assemble up to step 6, refrigerate up to 24 hours, add onions and bake before serving. Pairs well with roast turkey or chicken.

Tender green beans are coated in a rich sauce in this classic Old-School Green Bean Casserole recipe. Save
Tender green beans are coated in a rich sauce in this classic Old-School Green Bean Casserole recipe. | butterhearth.com

This recipe is sure to bring warmth to your holiday table. Enjoy every creamy, crunchy bite with loved ones.

Recipe Questions

How do I keep green beans tender but crisp?

Boil the green beans for about 5 minutes until just tender, then immediately rinse under cold water to stop cooking and preserve their bright color and crispness.

Can I use frozen green beans instead of fresh?

Yes, frozen cut green beans can be substituted; just thaw and drain them thoroughly before using to avoid extra moisture in the dish.

What kind of mushrooms work best for the sauce?

Cremini or button mushrooms are ideal as they provide a mild savory flavor and tender texture that complements the creamy sauce.

How do I get the topping crispy and golden?

Sprinkle crispy fried onions halfway through baking, then add more on top and bake until golden for a crunchy finish.

Can this dish be prepared ahead of time?

Yes, assemble the casserole up to adding the fried onions and refrigerate for up to 24 hours, then add the onions and bake before serving.

Old-School Green Bean Casserole

Tender green beans in a creamy mushroom sauce topped with crispy fried onions for a comforting side dish.

Prep duration
15 min
Time to cook
35 min
Complete duration
50 min
Created by Grace Mitchell


Skill Level Easy

Heritage American

Output 6 Portions

Dietary considerations Meat-Free

Components

Vegetables

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

Sauce Base

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

Topping

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

Directions

Stage 01

Preheat Oven: Set the oven to 350°F.

Stage 02

Blanch Green Beans: Bring a large pot of salted water to a boil. Add green beans and cook for 5 minutes until just tender and bright green. Drain and rinse under cold water to halt cooking. Set aside.

Stage 03

Cook Mushroom Mixture: Melt butter in a large skillet over medium heat. Add mushrooms and sauté for 5-6 minutes until browned and tender. Incorporate onion and garlic, cooking for an additional 2-3 minutes until softened.

Stage 04

Prepare Sauce: Stir in flour and cook for 1 minute while stirring constantly. Gradually whisk in milk, cream, and vegetable broth. Heat to a simmer and cook until thickened, approximately 5 minutes. Season with salt, pepper, and optional nutmeg.

Stage 05

Combine Beans and Sauce: Add drained green beans to the skillet, tossing thoroughly to coat them with the sauce.

Stage 06

Assemble in Baking Dish: Transfer the mixture to a 2-quart baking dish. Evenly sprinkle half of the crispy fried onions atop the mixture.

Stage 07

Bake Initial Layer: Bake for 25 minutes until the casserole is bubbling.

Stage 08

Add Final Topping and Continue Baking: Remove from oven, top with remaining fried onions, and bake for an additional 5 to 7 minutes until golden and crisp.

Stage 09

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

Necessary tools

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

Allergy details

Review each component for potential allergens and consider consulting with a healthcare provider if you're unsure about certain ingredients.
  • Contains milk (dairy), wheat (gluten in flour and fried onions), and possibly soy (in store-bought fried onions). Verify product labels.

Nutritional information (per portion)

These values are estimates only and shouldn't replace professional medical guidance.
  • Energy Value: 265
  • Fats: 15 g
  • Carbohydrates: 25 g
  • Protein Content: 6 g