Old-School Green Bean Casserole

Featured in: Comfort Bakes

This creamy casserole blends fresh green beans, earthy mushrooms, and sweet onions in a luscious sauce. A hint of nutmeg and a topping of crispy fried onions add savory crunch and nostalgic flavor, perfect for special gatherings. Easy steps and make-ahead tips ensure convenience, while classic oven baking delivers golden results. Pair with roasted poultry or serve on its own for a comforting vegetarian offering year-round. Loved for its rich taste and texture, it brings warmth and tradition to your table.

Updated on Sun, 09 Nov 2025 10:51:00 GMT
Creamy Old-School Green Bean Casserole topped with crispy fried onions, perfect for holidays.  Save
Creamy Old-School Green Bean Casserole topped with crispy fried onions, perfect for holidays. | ovenharmony.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 always brings back memories of holiday dinners at my grandmother's house, where the aroma of mushrooms and crispy onions filled the kitchen. Everyone looked forward to scooping a big portion onto their plates and reminiscing about family traditions.

Ingredients

  • Fresh Green Beans: 900 g (2 lb), trimmed and cut into 5 cm (2-inch) pieces (or substitute with 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 Cloves: 2, 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).
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.
Sauté Vegetables:
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.
Prepare 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 with Green Beans:
Add the drained green beans to the skillet and toss to coat evenly in the sauce.
Transfer to Baking Dish:
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.
Cool and Serve:
Let cool for 5 minutes before serving.
Delicious Old-School Green Bean Casserole: tender green beans in a rich mushroom sauce.  Save
Delicious Old-School Green Bean Casserole: tender green beans in a rich mushroom sauce. | ovenharmony.com

Last Thanksgiving, my niece helped sprinkle the crispy onions—she tried sneaking extra on top, making us all laugh. Sharing this dish together always brings a sense of warmth and connection.

Make Ahead Tips

You can assemble the casserole up to step 6 a day in advance. Store covered in the refrigerator and add the fried onions just before baking for best texture.

Serving Suggestions

This side works beautifully with roast turkey, grilled chicken, or even as a vegetarian entree alongside crusty bread and salad.

Customization Ideas

Try adding 50 g of grated sharp cheddar or Gruyère cheese to the sauce for extra flavor, or a pinch of cayenne for a gentle kick.

Classic Old-School Green Bean Casserole served hot, a must-have for family feasts. Save
Classic Old-School Green Bean Casserole served hot, a must-have for family feasts. | ovenharmony.com

This classic green bean casserole is the ultimate comfort food for any holiday gathering. Its creamy sauce and crispy topping make every bite memorable.

Recipe FAQ

How can I make this dish ahead?

Assemble through step 6, refrigerate up to 24 hours, then top with onions and bake before serving for optimal texture.

Can I use frozen green beans?

Yes, thaw and drain frozen cut green beans before cooking. They work well and save prep time.

What cheese works best for extra flavor?

Sharp cheddar or Gruyère blends nicely into the sauce, creating a richer, deeper taste experience.

How do I achieve crispy onions?

Use store-bought or homemade fried onions, bake until golden for the perfect crisp topping on your casserole.

Is this suitable for vegetarians?

Yes, the ingredients are vegetarian-friendly. Check fried onion and broth labels for added animal products.

What can I serve this with?

This side pairs wonderfully with roasted turkey, chicken, or other classic holiday mains for a balanced meal.

Old-School Green Bean Casserole

Creamy green beans baked with mushrooms and crispy onions. A nostalgic side for family and holiday meals.

Prep duration
15 min
Cook duration
35 min
Complete duration
50 min
Created by Claire Johnson

Classification Comfort Bakes

Complexity Easy

Heritage American

Output 6 Portions

Dietary considerations Meat-free

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

Phase 01

Prepare Oven: Preheat oven to 350°F.

Phase 02

Cook Green Beans: Bring a large pot of salted water to a boil. Add green beans and boil for 5 minutes until just tender. Drain and rinse with cold water to stop cooking. Set aside.

Phase 03

Sauté Vegetables: In a large skillet over medium heat, melt butter. Add mushrooms and cook until tender and browned, about 5-6 minutes. Stir in onion and garlic; sauté 2-3 minutes until softened.

Phase 04

Prepare Sauce: Sprinkle flour over vegetables and cook, stirring constantly, for 1 minute. Gradually whisk in milk, cream, and broth. Simmer until thickened, about 5 minutes. Season with salt, pepper, and nutmeg, if using.

Phase 05

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

Phase 06

Layer in Baking Dish: Transfer mixture to a 2-quart baking dish and sprinkle half of the fried onions on top.

Phase 07

Bake Main Layer: Bake for 25 minutes, until bubbling.

Phase 08

Add Final Topping: Remove from oven, top with remaining fried onions, and bake for 5-7 minutes more until golden and crisp.

Phase 09

Rest and Serve: 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 consult healthcare professionals if you're unsure about ingredients.
  • Contains milk (dairy), wheat (gluten in flour and fried onions), and soy (possible in store-bought fried onions). Review fried onion and broth packaging for potential allergens.

Nutritional information (each portion)

These values are approximate guidelines only and shouldn't replace professional medical guidance.
  • Energy: 265
  • Fats: 15 g
  • Carbohydrates: 25 g
  • Proteins: 6 g