Old-School Green Bean Casserole

Featured in: Flavorful Sides

Enjoy a comforting casserole featuring tender green beans enveloped in a creamy, homemade mushroom and onion sauce. This classic side is finished with layers of golden, crispy fried onions for a delightful crunch. Simple to prepare with everyday ingredients, it pairs beautifully with roast meats or as a stand-alone vegetarian dish. Perfect for holidays or family dinners, this dish combines nostalgia and rich flavor in every bite.

Updated on Sat, 08 Nov 2025 10:43:00 GMT
A delicious Old-School Green Bean Casserole topped with crispy fried onions awaits you.  Pin
A delicious Old-School Green Bean Casserole topped with crispy fried onions awaits you. | garlicgroove.com

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

I grew up watching this casserole come together every Thanksgiving, the smell of onions and mushrooms filling the kitchen. Now, it is the dish my family expects on every special gathering.

Ingredients

  • Fresh or Frozen Green Beans: 900 g (2 lb) trimmed and cut into 5 cm (2-inch) pieces, or use frozen cut green beans, thawed and drained
  • Unsalted Butter: 2 tbsp for sautéing
  • Cremini or Button Mushrooms: 250 g (9 oz), sliced
  • Yellow Onion: 1 small, finely chopped
  • Garlic Cloves: 2, minced
  • All-Purpose Flour: 2 tbsp for thickening the sauce
  • 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, for topping

Instructions

Preheat:
Preheat the oven to 180°C (350°F)
Cook Beans:
Bring a large pot of salted water to a boil Add green beans Cook for 5 minutes until just tender but still bright green Drain and rinse under cold water to stop cooking Set aside
Sauté 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 another 2-3 minutes until softened
Make Sauce:
Stir in 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:
Add drained green beans to the skillet Toss to coat evenly in the 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 more until golden and crisp
Finish:
Let cool for 5 minutes before serving
Creamy and savory Old-School Green Bean Casserole perfect for holiday gatherings.  Pin
Creamy and savory Old-School Green Bean Casserole perfect for holiday gatherings. | garlicgroove.com

This casserole is the dish my kids pile onto their plates first, asking for seconds before we've even sat down together. It always brings laughter and tradition to our table.

Required Tools

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

Allergen Information

Contains milk (dairy), wheat (gluten in flour and fried onions), and possibly soy (check fried onion labels and broth)

Nutritional Information

Each serving provides 265 calories, 15 g total fat, 25 g carbohydrates, and 6 g protein

Nostalgic Old-School Green Bean Casserole served with a festive twist on comfort. Pin
Nostalgic Old-School Green Bean Casserole served with a festive twist on comfort. | garlicgroove.com

Serve this casserole warm so the topping stays crisp and the sauce creamy. It pairs beautifully with any holiday main dish.

Recipe Questions

Can I use frozen green beans?

Yes, thawed frozen green beans work well and should be drained thoroughly before using.

How do I keep onions crispy?

Sprinkle half the fried onions before baking, and add the rest just before the final minutes for best crunch.

Can I make it ahead of time?

The dish can be assembled a day ahead. Add the fried onions and finish baking before serving.

Is there a dairy-free option?

Swap milk and cream with plant-based alternatives and check fried onions for dairy ingredients.

Does cheese enhance the flavors?

Adding sharp cheddar or Gruyère to the sauce provides an extra savory touch if desired.

What pairs well with this dish?

This side complements roast poultry, beef, or vegetarian mains for festive meals.

Old-School Green Bean Casserole

Tender green beans baked in creamy mushroom sauce, topped with crispy onions. Comforting side for any feast.

Prep duration
15 min
Cook duration
35 min
Complete duration
50 min


Complexity Easy

Heritage American

Output 6 Portions

Dietary requirements Vegetarian

Components

Vegetables

01 2 lb fresh green beans, trimmed and cut into 2-inch pieces, or 2 lb 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 1/2 cup heavy cream
08 1/2 cup low-sodium vegetable broth
09 1 teaspoon salt
10 1/2 teaspoon black pepper
11 1/2 teaspoon ground nutmeg (optional)

Topping

01 1 1/2 cups crispy fried onions (store-bought or homemade)

Directions

Step 01

Preheat Oven: Set oven temperature to 350°F.

Step 02

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

Step 03

Sauté Mushrooms and Aromatics: In a large skillet over medium heat, melt unsalted butter. Add sliced mushrooms and cook for 5 to 6 minutes until softened and browned. Incorporate the chopped onion and minced garlic, cooking 2 to 3 minutes until both are fully softened.

Step 04

Prepare Roux and Sauce: Stir in all-purpose flour; cook for 1 minute, stirring constantly. Gradually whisk in milk, heavy cream, and vegetable broth. Simmer and cook until thickened, about 5 minutes. Season with salt, black pepper, and nutmeg if desired.

Step 05

Combine Beans with Sauce: Add drained green beans to the skillet and gently toss to coat evenly with the sauce.

Step 06

Layer and Top: Transfer the mixture to a 2-quart baking dish. Sprinkle half the crispy fried onions over the top.

Step 07

Bake Until Bubbling: Bake in preheated oven for 25 minutes until hot and bubbling.

Step 08

Finish with Remaining Onions: Remove from oven, add the remaining crispy fried onions on top, and bake for an additional 5 to 7 minutes until golden and crisp.

Step 09

Rest and Serve: Let the casserole cool for 5 minutes before serving.

Necessary tools

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

Allergy details

Review each ingredient for potential allergens and speak with a healthcare provider if you're uncertain about anything.
  • Contains milk (dairy), wheat (gluten in flour and fried onions), and soy (may be present in store-bought fried onions); confirm labels for allergen information on processed ingredients.

Nutrition breakdown (per portion)

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