Classic Green Bean Casserole

Prep Time	Cook Time	Total Time
20 min	35 min	55 min

How to Make Classic Green Bean Casserole

Prep mode (keeps screen active)

Preheat oven and prepare baking dish

Preheat your oven to 375°F and place a rack in the center position.
Lightly grease a 2-quart baking dish with butter or cooking spray and set it aside.
Blanch the green beans

Bring a large pot of water to a boil and season it with the teaspoon of salt.
Add the green beans and cook until crisp-tender and bright green, 4 to 5 minutes.
Drain the beans and immediately transfer them to a bowl of ice water to stop the cooking.

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Dry and arrange the beans

Once cool, drain the beans again and pat them very dry with clean kitchen towels.
Spread the beans evenly in the prepared baking dish and set the dish aside.
Cook the aromatics and mushrooms

In a large skillet, melt the butter over medium heat until foamy but not browned.
Add the onion and cook, stirring often, until softened and translucent, about 5 minutes.
Stir in the garlic and cook just until fragrant, about 30 seconds.
Add the sliced mushrooms and cook, stirring occasionally, until they release their liquid and begin to brown, 6 to 8 minutes.
Make the creamy mushroom sauce

Sprinkle the flour evenly over the mushroom mixture and cook, stirring constantly, for 1 to 2 minutes.
Slowly pour in the milk while whisking, then add the vegetable broth and bouillon, whisking until smooth.
Season with the black pepper, dried thyme, and a pinch of nutmeg, then bring the sauce to a gentle simmer.
Cook, stirring often, until the sauce has thickened enough to coat the back of a spoon, 4 to 6 minutes.

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Combine beans and sauce

Pour the hot mushroom sauce evenly over the green beans in the baking dish and gently toss to coat.
Spread the mixture into an even layer so the topping will brown evenly later.
Mix the crunchy topping

In a medium bowl, combine the crispy fried onions, panko breadcrumbs, grated Parmesan, and olive oil.
Toss until the onions and crumbs are evenly coated with the oil and the mixture feels slightly moist.
Top and bake the casserole

Sprinkle the topping evenly over the sauced green beans, covering the surface from edge to edge.
Bake until the casserole is bubbling around the edges and the topping is deep golden brown, 18 to 22 minutes.
Let the casserole rest for 10 minutes before serving so the sauce can thicken slightly.

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Substitutions

Fresh green beans -> Frozen green beans: You can use frozen cut green beans instead of fresh, and skip the trimming step. Blanch them straight from frozen for just 2 to 3 minutes so they stay firm and vibrant.
Milk and Parmesan -> Nondairy milk and vegan Parmesan: For a dairy-free version, swap the milk for unsweetened almond, oat, or soy milk and use vegan Parmesan. Replace the butter with your favorite plant-based butter so the sauce still tastes rich and silky.
Panko and fried onions -> Crushed kettle-cooked potato chips: For a fun twist, trade the panko and some fried onions for crushed kettle-cooked potato chips on top. They bring big crunch and a salty, snacky flavor that people love with creamy casseroles.

Tips

Salt your blanching water well: Properly salted water seasons the beans from the inside, so they taste flavorful even before meeting the sauce.
Dry beans mean thicker, creamier sauce: If the beans are damp, they shed water into the sauce, which can make the casserole loose and watery.
Grate your own Parmesan: Freshly grated Parmesan melts more smoothly into the topping and gives better nutty flavor than the pre-grated kind.
Bake on a sheet pan for easy handling: Place the baking dish on a sheet pan to catch any bubbling overflow and make it easier to move safely.
Adjust the sauce thickness before baking: If the sauce seems too thin, simmer it a few extra minutes; if too thick, whisk in a splash more milk.

Energy	199	kcal
Protein	7	g
Total Fat	10	g
Carbohydrates	20	g
Dietary Fiber	4	g

FAQ

Can I assemble this green bean casserole ahead of time?: Yes, assemble the casserole without the topping and refrigerate it tightly covered for up to 24 hours. Let it sit at room temperature about 20 minutes, add the topping, then bake until hot and bubbly.
Why did my casserole turn out watery?: The most common reasons are under-thickened sauce or beans that were not dried well after blanching. Next time, simmer the sauce longer and really blot the beans dry before adding the sauce.
Can I use canned green beans instead of fresh?: You can, but the texture will be much softer and more like the classic canned-soup version. Skip blanching, drain them very well, and reduce the baking time by about 5 minutes.
How can I make this recipe vegetarian-friendly with Parmesan?: Traditional Parmesan is not vegetarian, so look for a hard Italian-style cheese specifically labeled vegetarian or rennet-free. You can also use shredded sharp cheddar or Gruyere, which both taste great in the crunchy topping.