I love bringing this vegan green bean casserole to Thanksgiving because it has everything I want in a holiday side: tender green beans, a creamy mushroom sauce, and plenty of crisp onions. It is cozy, easy to prepare ahead, and just as welcome at a weeknight dinner as it is on a festive table.
Why You’ll Love This Vegan Green Bean Casserole
This casserole is made from simple ingredients and has a rich, savory sauce without canned soup. Mushrooms, garlic, and vegetable broth create plenty of flavor, while unsweetened plant milk keeps the sauce creamy. You can assemble it in advance, then bake it with the crunchy onion topping just before serving.
Vegan Green Bean Casserole Ingredients & Substitutions
- 2 pounds fresh green beans, trimmed and cut into 2-inch pieces
- 3 tablespoons vegan butter
- 12 ounces cremini mushrooms, thinly sliced
- 1 small yellow onion, finely diced
- 2 cloves garlic, minced
- 3 tablespoons all-purpose flour
- 1 cup vegetable broth
- 1 cup unsweetened oat milk or soy milk
- 1 tablespoon soy sauce or tamari
- 1/2 teaspoon dried thyme
- 1/4 teaspoon black pepper
- 1/2 teaspoon salt, plus more for the cooking water
- 1 1/2 cups vegan crispy fried onions, divided
Use tamari instead of soy sauce for a gluten-free option, and choose a gluten-free flour and crispy onion topping if needed. Unsweetened cashew milk also works well in the sauce. Frozen green beans can stand in for fresh, but thaw and drain them well before assembling the casserole.
Step-by-Step Instructions to Make Vegan Green Bean Casserole
1. Prepare the green beans
Heat the oven to 375°F (190°C). Bring a large pot of salted water to a boil, add the green beans, and cook for 4 to 5 minutes, until bright green and just tender. Drain them, then rinse briefly with cool water to stop the cooking.
2. Make the mushroom sauce
Melt the vegan butter in a large skillet over medium heat. Add the mushrooms and diced onion, and cook for 7 to 9 minutes, stirring now and then, until the mushrooms soften and their moisture cooks away. Stir in the garlic and cook for 30 seconds.
3. Thicken the sauce
Sprinkle the flour over the mushroom mixture and stir until everything is coated. Slowly pour in the vegetable broth while stirring, then add the plant milk, soy sauce, thyme, pepper, and salt. Simmer for 3 to 5 minutes, stirring often, until the sauce is creamy and thick enough to coat a spoon.
4. Assemble and bake
Fold the green beans and 1/2 cup of the crispy fried onions into the sauce. Spoon the mixture into a 9-by-13-inch baking dish and bake uncovered for 20 minutes, until bubbling around the edges.
5. Add the crispy topping
Scatter the remaining crispy fried onions over the casserole. Bake for another 5 to 8 minutes, until the topping is golden and crisp. Let the casserole rest for 5 minutes before serving.
Tips for Success
- Blanch the beans just until tender. They will continue to soften in the oven, so a little bite at this stage is ideal.
- Let the mushrooms cook until their released moisture has mostly evaporated. This helps keep the sauce rich instead of watery.
- Add the final layer of crispy onions near the end of baking so it stays crunchy.
- Taste the sauce before assembling and adjust the salt and pepper to suit your vegetable broth and soy sauce.
Variations of Vegan Green Bean Casserole
For extra depth, add 1/2 teaspoon smoked paprika or a pinch of nutmeg to the sauce. Stir in 1/2 cup toasted sliced almonds for another layer of crunch, or swap half the mushrooms for finely chopped shallots. For a brighter finish, add a small squeeze of lemon juice to the sauce just before mixing it with the beans.
Serving Suggestions: What to Pair with Vegan Green Bean Casserole
This casserole fits right in beside Thanksgiving favorites such as mashed potatoes, roasted squash, cranberry sauce, and stuffing. It also makes a comforting side for a simple dinner of baked potatoes or roasted vegetables. For a holiday spread, serve it warm in the baking dish so everyone can scoop up plenty of creamy beans and crisp onions.
Storage & Reheating Instructions
Cool leftovers, then store them in an airtight container in the refrigerator for up to 4 days. Reheat individual portions in the microwave, or warm a larger amount covered in a 350°F (175°C) oven until hot. The onion topping softens as it sits, so add a fresh handful of crispy onions before reheating if you want extra crunch. To make the casserole ahead, prepare the beans and sauce, combine them in the baking dish, cover, and refrigerate for up to 24 hours. Add a few minutes to the baking time if it goes into the oven cold, and add the topping near the end.
Memories Made Around the Table
I love the moment this casserole comes out of the oven, with the mushroom sauce bubbling gently beneath its golden onion topping. It is the kind of side dish that invites everyone to pass the spoon around and linger at the table a little longer. On Thanksgiving, I like to set it beside the other favorites and let each person build a plate their own way.
FAQs
Can I make vegan green bean casserole ahead of time?
Yes. Assemble the beans and sauce in the baking dish, cover, and refrigerate for up to 24 hours. Bake until hot and bubbling, then add the crispy onion topping for the final few minutes.
Can I use frozen green beans?
Yes. Thaw them completely and drain away excess water before mixing them with the sauce. There is no need to blanch thawed green beans.
How can I make the sauce gluten-free?
Use a gluten-free all-purpose flour blend, tamari instead of soy sauce, and crispy fried onions that are labeled gluten-free. Check that your vegetable broth is gluten-free as well.
Why is my casserole watery?
Extra water can come from undercooked mushrooms or wet green beans. Cook the mushrooms until their moisture evaporates, and drain the beans thoroughly before combining them with the sauce.
Final Thoughts
This vegan green bean casserole brings creamy, savory flavor and a crunchy finish to the Thanksgiving table without making the cooking feel complicated. Prepare it ahead, bake it until bubbling, and serve it warm alongside the holiday dishes you love.
Vegan Green Bean Casserole
Equipment
- 1 Large Pot
- 1 Large Skillet
- 1 9 by 13 inch baking dish
Ingredients
- 2 pounds fresh green beans trimmed and cut into 2-inch pieces
- 3 tablespoons vegan butter
- 12 ounces cremini mushrooms thinly sliced
- 1 small yellow onion finely diced
- 2 cloves garlic minced
- 3 tablespoons all-purpose flour
- 1 cup vegetable broth
- 1 cup unsweetened oat milk or soy milk
- 1 tablespoon soy sauce or tamari
- 0.5 teaspoon dried thyme
- 0.25 teaspoon black pepper
- 0.5 teaspoon salt plus more for the cooking water
- 1.5 cups vegan crispy fried onions divided
Instructions
- Heat the oven to 375°F (190°C). Bring a large pot of salted water to a boil, add the green beans, and cook for 4 to 5 minutes, until bright green and just tender. Drain them, then rinse briefly with cool water to stop the cooking.
- Melt the vegan butter in a large skillet over medium heat. Add the mushrooms and diced onion, and cook for 7 to 9 minutes, stirring now and then, until the mushrooms soften and their moisture cooks away. Stir in the garlic and cook for 30 seconds.
- Sprinkle the flour over the mushroom mixture and stir until everything is coated. Slowly pour in the vegetable broth while stirring, then add the plant milk, soy sauce, thyme, pepper, and salt. Simmer for 3 to 5 minutes, stirring often, until the sauce is creamy and thick enough to coat a spoon.
- Fold the green beans and 1/2 cup of the crispy fried onions into the sauce. Spoon the mixture into a 9-by-13-inch baking dish and bake uncovered for 20 minutes, until bubbling around the edges.
- Scatter the remaining crispy fried onions over the casserole. Bake for another 5 to 8 minutes, until the topping is golden and crisp. Let the casserole rest for 5 minutes before serving.