Vegan Green Bean Casserole Recipe with Crispy Onion Topping

This quick and easy vegan green bean casserole (without mushrooms) delivers an elegant, flavorful side dish in minimal time. Fresh green beans are cooked until just tender, tossed in a creamy mustard cashew sauce, and finished with a crunchy fried onion topping. Skipping mushrooms creates a lighter, faster version of the classic American Thanksgiving side, and making it dairy-free keeps it even more delicate. It looks impressive on the table, yet comes together in under 15 minutes, so you may find yourself serving it year-round, not just at Thanksgiving.

Although I’m not American and didn’t grow up with Thanksgiving traditions, this green bean casserole quickly became a favourite whenever we celebrate with friends. Living abroad has introduced me to many international dishes, and after trying this classic, I understood why it’s so popular. I developed a vegan version using a cashew-based cream sauce, with a mustardy twist for extra brightness and depth.

Why no mushrooms?

There’s nothing wrong with mushrooms, but I left them out for two reasons. First, omitting mushrooms keeps the dish lighter, which pairs nicely with a rich main course. Second, leaving out mushrooms makes this recipe faster and simpler — ideal when you’re preparing multiple dishes for guests. To make up for the missing mushroom flavour, I add mustard and nutritional yeast to the cashew cream for a savory, satisfying sauce.

Ingredients

• Fresh green beans (French beans) – I prefer fresh or frozen for a firmer texture; canned beans can be too soft. Blanch them briefly so they keep a pleasant bite.
• Cashews – the base of the creamy sauce. Macadamias can be substituted if you need a cashew-free option, though they should be soaked first.
• Vegetable stock – use your usual stock cube or powder, watching salt levels and adjusting seasoning as needed.
• Nutritional yeast – adds a slight cheesy umami and contributes vitamin B12 for many vegans.
• Fried onions – store-bought crispy fried onions are an easy and tasty choice here, though homemade will work if you prefer.
• Wholegrain mustard & English mustard powder – the wholegrain adds texture while the powder gives heat. Dijon can be used if you prefer a single mustard. Adjust heat for children as needed.
• Seasonings – garlic powder, nutmeg, salt and black pepper for rounded flavour.

Please see the recipe card below for exact ingredient quantities and full instructions.

Basic Instructions

• Top and tail the green beans, then blanch and refresh: boil 4–5 minutes until bright green and just tender, then plunge into iced water to stop cooking.
• Make the mustardy cashew cream by blending the cashews, stock, nutritional yeast, mustards and seasonings until very smooth.
• Combine the beans and sauce in a casserole dish, top with fried onions, and bake for about 10 minutes until heated through and the topping is crisp.

This is a summary. See the recipe card below for full step-by-step instructions and measurements.

Chef’s Tips

• Start with less salt and taste as you go. Saltiness varies by type and brand, so add gradually—it’s easier to add more than to remove it.
• This recipe yields a generous amount of sauce. You may not need it all depending on your dish shape; save any extra for another use.

Serving suggestions

This casserole is classic with a roast. For a fully vegan Thanksgiving or holiday meal, serve it alongside nut roast or stuffed pumpkin, roast potatoes or boulangère potatoes, and extra vegetables such as buttered carrots and swede or roasted beetroot. Add a rich onion gravy and a cranberry sauce for a complete, festive plate.

Variations

• Using frozen green beans? Blanch for 3–4 minutes instead of 4–5, since they cook faster.
• Allergic to cashews? Use soaked macadamias, which should be pre-soaked for several hours to blend smoothly.
• If your blender isn’t high-speed, soak cashews in boiling water for 15 minutes (or cold water for 6–8 hours) before blending.
• Missing mushrooms? Sauté sliced mushrooms and fold them into the beans and sauce before baking.

Making ahead

Prepare and chill blanched green beans for 2–3 days and store the cashew sauce separately. On the day, bring the beans and sauce to room temperature for about 30 minutes, combine, top with fried onions and bake 10–15 minutes. If the casserole is still cool in the center, extend the baking time until heated through.

Storage & Leftovers

Store leftovers in an airtight container in the fridge for up to 3 days. Reheat in the microwave, oven, or air fryer with a lid or foil to prevent drying out; add a splash of water if the sauce has thickened. Reheat in a vessel sized to the amount remaining so the sauce doesn’t spread too thin and dry out.

📖 Recipe 📖

Vegan Green Bean Casserole

An indulgent mustard cashew cream sauce dresses tender green beans for a quick, dairy-free version of this Thanksgiving classic.

Prep Time
5 mins

Cook Time
15 mins

Total Time
20 mins

Servings:
6 people

Ingredients

• 500 g green beans, topped and tailed

Cashew sauce:

• 135 g cashews
• 360 ml vegetable stock
• 15 g nutritional yeast
• 1 teaspoon wholegrain mustard
• 1 teaspoon dry English mustard powder
• ½ teaspoon garlic powder
• ½ teaspoon salt
• Black pepper and a pinch of nutmeg

Topping:

• ½ cup fried onions
• Fresh herbs for garnish (optional)

Instructions

1. Preheat the oven to 180°C / 375°F.
2. Top and tail the green beans. Cook in salted boiling water for 4–5 minutes until bright green and just tender. Immediately drain and plunge into iced water to stop the cooking.
3. Make the cashew sauce: blend cashews, vegetable stock, nutritional yeast, wholegrain mustard, dry English mustard powder, garlic powder, salt, pepper and nutmeg until very smooth. If your blender isn’t high-speed, soak cashews first.
4. Place the green beans in a casserole dish and pour the sauce over them, mixing to combine.
5. Sprinkle the fried onions evenly over the top and season lightly with salt and pepper.
6. Bake for 10 minutes until warmed through. Garnish with fresh thyme or parsley before serving.

Notes

• If using frozen green beans, reduce blanching time to 3–4 minutes.
• If you don’t have a high-speed blender, soak the cashews in boiling water for 15 minutes or in cold water for 6–8 hours before blending.
• Start with less salt and adjust to taste, as saltiness varies by brand.
• You may not need all the sauce—add to your preferred consistency and save any extra.

Nutrition

Calories: 197 kcal |
Carbohydrates: 17 g |
Protein: 7 g |
Fat: 13 g

If you like this recipe, please leave a star rating on the recipe card!

More Recipes

If you enjoyed this dairy-free vegan green bean casserole, you might also like these complementary vegan and gluten-free dishes for a full roast dinner:

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