Green Bean Casserole Dish (Printable)

Tender green beans coated in a creamy mushroom sauce and topped with crispy fried onions.

# Ingredient List:

→ Vegetables

01 - 1 lb fresh green beans, trimmed and cut into 2-inch pieces (or 1 lb frozen, thawed)
02 - 1 small yellow onion, finely chopped
03 - 2 cloves garlic, minced
04 - 8 oz cremini or button mushrooms, sliced

→ Sauce

05 - 2 tbsp unsalted butter
06 - 2 tbsp all-purpose flour
07 - 1 cup whole milk
08 - 1/2 cup low-sodium vegetable broth
09 - 1/2 cup sour cream
10 - 1/2 tsp salt
11 - 1/4 tsp black pepper
12 - 1/4 tsp ground nutmeg

→ Topping

13 - 1 1/2 cups crispy fried onions (store-bought or homemade)

# Directions:

01 - Preheat the oven to 350°F.
02 - Bring a large pot of salted water to a boil. Add green beans and cook for 4–5 minutes until bright green and just tender. Drain and immediately transfer to a bowl of ice water to stop the cooking. Drain again and set aside.
03 - Melt butter in a large skillet over medium heat. Add chopped onion and cook for 2–3 minutes until softened. Add garlic and mushrooms; cook for 5 minutes until mushrooms are tender and liquids evaporate.
04 - Stir in flour and cook for 1 minute while stirring constantly. Gradually whisk in whole milk and vegetable broth. Continue cooking, stirring frequently, until the sauce thickens, about 3–4 minutes.
05 - Remove skillet from heat. Stir in sour cream, salt, black pepper, and ground nutmeg until smooth.
06 - Add drained green beans to the sauce and toss to coat evenly.
07 - Transfer the mixture to a greased 2-quart baking dish. Sprinkle 1 cup of crispy fried onions evenly over the top.
08 - Bake for 25 minutes until the casserole is bubbling.
09 - Remove from the oven, sprinkle the remaining crispy fried onions on top, and bake an additional 5 minutes until golden brown.
10 - Let the dish rest for 5 minutes before serving.

# Expert Tips:

01 -
  • It feels fancy enough to impress guests, but honest enough that even a rushed weeknight dinner feels complete.
  • The contrast between creamy sauce and crunchy onions is genuinely addictive and stays crispy until the last bite.
  • You can make it hours ahead, which means one less thing to panic about when guests arrive.
02 -
  • If you skip the ice bath on the blanched beans, they keep cooking and turn olive-colored and mushy—the ice bath is not optional, it's everything.
  • Sour cream can curdle if you add it to a sauce that's still actively cooking; waiting until the skillet is off heat is the difference between silky sauce and grainy sauce.
  • Crispy onions absorb moisture if they sit on top too long before serving, so if you're making this ahead, store the onions separately and sprinkle them on just before baking.
03 -
  • Toast the raw mushrooms briefly in a dry skillet before adding butter and onions—this releases their moisture first so they brown instead of steam, deepening their flavor dramatically.
  • Save a handful of fried onions uncooked and sprinkle them on top at the very end; they stay impossibly crispy against the warm casserole and add textural contrast that changes everything.
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