Green Bean Casserole Crispy Onions (Printable)

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

# What You'll Need:

→ Vegetables

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

→ Sauce

05 - 3 tbsp unsalted butter
06 - 3 tbsp all-purpose flour
07 - 1 1/4 cups whole milk
08 - 1/2 cup vegetable or chicken broth
09 - 1/2 cup sour cream
10 - 1 tsp salt
11 - 1/2 tsp black pepper
12 - 1/4 tsp ground nutmeg

→ Topping

13 - 1 1/2 cups crispy fried onions

# How-To Steps:

01 - Preheat oven to 375°F. Grease a 2-quart baking dish with butter or cooking spray.
02 - Bring a pot of salted water to boil. Blanch fresh green beans for 4 minutes until just tender-crisp. Drain immediately and rinse under cold water to stop cooking and preserve bright green color.
03 - Melt butter in a large skillet over medium heat. Add chopped onion and sauté until softened, approximately 3 minutes. Add sliced mushrooms and cook until tender and liquid has evaporated, about 5 minutes. Stir in minced garlic and cook for 1 minute until fragrant.
04 - Sprinkle flour over the vegetable mixture, stirring constantly for 1 minute to cook out raw flour taste. Gradually whisk in milk and broth, ensuring no lumps form. Bring to a gentle simmer and cook for 2-3 minutes until sauce thickens enough to coat the back of a spoon.
05 - Remove skillet from heat. Stir in sour cream, salt, black pepper, and nutmeg until fully incorporated. The sour cream adds tanginess and prevents the sauce from becoming too heavy.
06 - Add prepared green beans to the sauce. Gently fold to coat evenly. Transfer the entire mixture to the prepared baking dish, spreading into an even layer.
07 - Bake uncovered for 20 minutes until the sauce is bubbly and the beans are heated through completely.
08 - Remove dish from oven and evenly distribute crispy fried onions across the top. Return to oven and bake for 10 minutes until onions are golden brown and the casserole is bubbling around the edges.
09 - Let the casserole rest for 5 minutes before serving. This allows the sauce to set slightly, making it easier to scoop and ensuring each portion holds its shape.

# Expert Advice:

01 -
  • The homemade mushroom sauce puts canned soup versions to shame while still being simple enough for a weeknight
  • Those crispy onions on top create this incredible crunch that makes everyone reach for seconds
02 -
  • Don't skip blanching fresh beans or they will end up disappointingly tough in the finished casserole
  • The sauce will look thin when you first add the liquid but it thickens beautifully as it simmers
03 -
  • Use a wide shallow baking dish instead of a deep one so more surface area gets covered in crispy onions
  • Let the casserole rest for 5 minutes before serving so the sauce sets up slightly

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