Name: Vegan Green Bean Casserole with Crispy Onions Recipe
Prep time: 20 min
Cook time: 58 min
Total time: 1 h 18 min
Cuisine: American
Ingredients: 2 medium onions, thinly sliced; ¼ cup oat flour; 2 tablespoons panko bread crumbs, gluten-free, if needed; 1 teaspoon sea salt; Nonstick cooking spray; ½ cup cashews, soaked; 1 cup unsweetened almond milk, or milk of choice; 24 oz fresh green beans, rinsed, trimmed and halved; 2 tablespoons vegan butter; 12 oz baby portobello mushrooms, trimmed and cut into ½-inch pieces; 1 teaspoon ground pepper; 3 cloves garlic, minced; ¼ teaspoon ground nutmeg; 2 tablespoons oat flour; 1 cup vegetable broth; 1 teaspoon low-sodium tamari, or soy sauce

There’s something irresistibly cozy about a classic casserole, isn’t there? This Vegan Green Bean Casserole with Crispy Onions Recipe takes that comforting idea and layers in fresh green beans, creamy cashew sauce, and the crunchiest baked onions. Trust me, once you make it, it becomes a new favorite to share year-round.

A white baking dish filled with a green bean casserole. The bottom layer has green beans, bright green and slightly shiny. Above the beans is a creamy brownish sauce with small pieces of mushrooms. The top layer is a thick, crispy layer of golden brown and darker fried onion strings spread evenly over the casserole. The dish is placed on a white marbled surface with a striped cream and white cloth underneath. Nearby is a spoon with a wooden handle. Photo taken with an iphone --ar 2:3 --v 7

Jump to:

Why You'll Love This Recipe
Ingredients & Why They Work
Make It Your Way
Step-by-Step: How I Make Vegan Green Bean Casserole with Crispy Onions Recipe
Top Tip
How to Serve Vegan Green Bean Casserole with Crispy Onions Recipe
Make Ahead and Storage
Frequently Asked Questions:
Final Thoughts
Vegan Green Bean Casserole with Crispy Onions Recipe

Why You'll Love This Recipe

Honestly, I fell in love with this recipe because it finally gave me that nostalgic green bean casserole vibe without any canned soup or dairy in sight. It’s fresh, flavorful, and the crispy onions? Absolute game-changers.

Fresh & wholesome: Uses whole ingredients like fresh green beans and mushrooms instead of processed soup mixes.
Delicious creamy sauce: The cashew cream base is silky and rich, giving the casserole a perfect, comforting texture.
Crispy onion topping: Baking your own crispy onions means you avoid the greasy store-bought fried ones but get all the crunch and flavor.
Simple to customize: This recipe adapts beautifully to what you have on hand or your personal taste preferences.

Ingredients & Why They Work

Each ingredient in this Vegan Green Bean Casserole with Crispy Onions Recipe plays a key role. They come together to build layers of flavor and texture — from the creamy sauce to the crunch on top. Here’s a little insight on the main players before you start shopping:

Flat lay of fresh green beans, trimmed and halved, bright green and crisp; thinly sliced medium yellow onions in a neat pile; small heap of raw cashews with creamy beige tones; baby portobello mushrooms cut into pieces, deep brown and fresh; three whole garlic cloves with papery white skins; a small white ceramic bowl filled with smooth unsweetened almond milk; another small white bowl containing golden vegan butter cubes; a third small white bowl holding light brown oat flour; a fourth small white bowl with golden gluten-free panko bread crumbs; a fifth small white bowl with coarse sea salt crystals; a sixth small white bowl of dark low-sodium tamari sauce; a small white bowl filled with golden vegetable broth; and a pinch of ground nutmeg and ground black pepper arranged as fine piles on the white surface, all ingredients arranged in perfect symmetry on simple white ceramic bowls, placed on a clean white marble surface, soft natural light, photo taken with an iPhone, professional food photography style, fresh ingredients, white ceramic bowls, no bottles, no duplicates, no utensils, no packaging --ar 2:3 --v 7 --p m7354615311229779997

Onions: Thinly sliced for maximum crispiness when baked into those golden, crunchy topping pieces.
Oat flour & panko breadcrumbs: Work together to coat the onions for that perfect crispy texture without frying.
Cashews: Soaked and blended to make a naturally creamy, dreamy sauce base that’s dairy-free but indulgent.
Unsweetened almond milk: Keeps the sauce smooth without adding extra sweetness or heaviness.
Fresh green beans: Blanched so they’re tender yet still have a satisfying snap, making the casserole lively and fresh.
Baby portobello mushrooms: Add umami depth and meaty texture to the sauce, balancing the creaminess with savory notes.
Vegan butter: Adds richness and helps sauté the mushrooms beautifully.
Garlic & nutmeg: Subtle aromatics that layer extra dimension into the overall flavor.
Vegetable broth & tamari: Bring that savory, slightly salty kick to tie everything together in the sauce.

Note: Exact ingredients and measurements are listed in the recipe card below.

Make It Your Way

I love mixing up the mushrooms sometimes for more earthy shiitakes or cremini, depending on what’s in season or on sale. You absolutely can swap almond milk for any plant milk you prefer — I’ve even used oat milk for a little extra creaminess!

Variation: Once, I added a teaspoon of smoked paprika to the sauce and it gave the casserole a subtle smoky twist that my family adored.
Seasonal swaps: Swap green beans for asparagus or broccolini in spring for a fresh twist.
Make it gluten-free: Use gluten-free panko or crushed gluten-free crackers for the crispy topping without sacrificing crunch.

Step-by-Step: How I Make Vegan Green Bean Casserole with Crispy Onions Recipe

The dish shows a single layer of green beans mixed with a creamy sauce that has small pieces of mushrooms and other vegetables. On top, there is a crispy light brown layer of thin fried onions that adds texture. The food is served in a white bowl with a wooden-handled fork placed on the left side inside the bowl. The background is a white marbled surface with soft natural light. photo taken with an iphone --ar 2:3 --v 7

Step 1: Soak and Toast the Crispy Onions

Start by soaking your cashews — this is key for a lustrous sauce later on. Next, preheat your oven high to 475°F to get those onions extra crispy. Toss sliced onions with oat flour, panko, and salt so every slice is well coated. Spread them evenly on a sprayed baking sheet, then bake for about 25 minutes, tossing every 10 minutes so they brown evenly without burning. When they’re beautifully golden and crisp, set them aside. This step is where the magic *really* begins; homemade crispy onions always overshadow the store-bought ones, promise.

Step 2: Blanch the Green Beans

While your onions bake, bring a pot of salted water to a boil and blanch the green beans for five minutes. Right after, plunge them into ice water to stop the cooking instantly. This keeps them bright and crisp-tender — no mush allowed here! Let them drain well before moving on.

Step 3: Cook the Mushroom Sauce

Drain your soaked cashews and whirl them in a blender with the almond milk until creamy and perfectly smooth. Meanwhile, melt vegan butter in a large skillet, sauté mushrooms with pepper and garlic, then sprinkle oat flour over to create a light roux. Gradually add vegetable broth and tamari, simmer briefly, and stir in the cashew cream. Keep it on medium-low, stirring occasionally, until thickened — about 6–8 minutes. This sauce is silky, comforting, and the heart of the casserole's creaminess.

Step 4: Assemble and Bake

Mix the green beans, half of the crispy onions, and the mushroom sauce gently in a large bowl. Transfer everything to an 8×8 baking dish, then top with the remaining onions to lock in the crunch. Bake at 375°F for about 15 to 20 minutes until bubbly and warmed through. Serve right away for the best texture contrast.

Top Tip

This recipe really shines when you give attention to the crispy onions and sauce consistency. I’ve learned the hard way that tossing the onions every 10 minutes helps avoid burnt edges while ensuring crispy goodness all over.

Crispy Onion Care: Make sure your onions are sliced thin but intact so they crisp evenly without turning floppy.
Cashew Cream Smoothness: Blend soaked cashews and almond milk long enough for a super smooth sauce — no lumps, no gritty texture.
Don't Skip the Ice Bath: Blanching and immediately shocking beans keeps their vibrant color and bite, which really elevates the dish.
Baking Temperature: >Start crispy onions at a high heat, then lower the temp for the casserole bake to avoid overcooking toppings.

How to Serve Vegan Green Bean Casserole with Crispy Onions Recipe

vegan green bean casserole - Serving Suggestion

Garnishes

I often sprinkle a little fresh chopped parsley or thyme right before serving. It adds a fresh herbal note that brightens the whole casserole and makes it look pretty too. Sometimes a pinch of smoked paprika goes on top with the onions for a touch of color and warmth.

Side Dishes

This casserole pairs beautifully with roasted potatoes or a light quinoa salad if you want a balanced meal. For holiday dinners, I love serving it alongside mashed potatoes and cranberry sauce—you’ll impress vegans and non-vegans alike!

Creative Ways to Present

For a dinner party, try individual mini casseroles in ramekins topped with a few extra crispy onions. They look elegant, and guests love having their own personal dish. Or layer the casserole in a clear baking dish so the beautiful bean and mushroom layers peek through the sides.

Make Ahead and Storage

Storing Leftovers

I store leftover casserole in an airtight container in the fridge and it holds beautifully up to 5 days. The crispy onions soften a bit in the fridge, but reheating in the oven helps them regain some crunch.

Freezing

To freeze, assemble the casserole but skip the baking step. Wrap it tightly in foil or plastic wrap and freeze for up to 2 months. When ready, just bake it from frozen at 375°F, adding a little extra time until heated through and bubbly.

Reheating

I prefer reheating leftovers in the oven or toaster oven at 350°F for about 15 minutes so it warms evenly and the topping gets a little crisp again. Avoid microwaving if you want to keep the texture from getting soggy.

Frequently Asked Questions:

Can I make the crispy onions ahead of time?

Absolutely! You can bake the crispy onions a day or two ahead and store them in an airtight container at room temperature. Just add them right before baking to keep their crunch.

What if I’m allergic to nuts?

If you’re nut-free, you can try substituting the cashew cream with a mixture of soaked sunflower seeds and water blended until smooth, or use a store-bought vegan cream alternative. Texture might vary slightly, but it still tastes great.

Can I use frozen green beans?

Yes, frozen green beans work fine. Just thaw and drain well before blanching or adding to the sauce so the casserole doesn’t get watery.

How do I get the sauce to thicken perfectly?

Make sure to cook the sauce over medium-low heat and stir occasionally. The oat flour combined with cashew cream thickens it nicely. If it seems thin, give it a few more minutes or add a touch more oat flour mixed with water beforehand.

Final Thoughts

This Vegan Green Bean Casserole with Crispy Onions Recipe holds a special place in my heart because it proves comfort food can be fresh, vibrant, and cruelty-free all at once. It’s perfect for holidays or simple family dinners when you want something a bit nostalgic but made thoughtfully. I can’t wait for you to try it — and tell me if your crispy onions turn out as addictive as mine!