Vegan Broccoli Casserole
Add Preferred SourceVegan Broccoli Casserole is that one side dish that ends up stealing the spotlight. The sauce starts with mushrooms and garlic, but as it simmers, it becomes richer than you’d expect without any cream or cheese. By the time everything bakes together, you’ve got this savory, bubbling casserole that’s hard to stop eating.
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I make this casserole for Thanksgiving, Christmas dinner, and holiday potlucks because it’s a crowd-favorite that’s hearty enough to satisfy everyone, even non-vegans. It’s also great for weeknight family dinners when you need something filling and comforting. It keeps in the fridge for 4 days and freezes beautifully for up to 3 months.
Ingredients You’ll Need
You’ll need all the ingredients shown in the photograph below.
How to Make Vegan Broccoli Casserole with Step-By-Step Instructions
Scroll down for the full recipe card containing a full printable recipe and measurements in both US customary and metric units.
Here’s how to make this creamy, savory casserole from start to finish.
Preheat the Oven
Preheat your oven to 375°F so it’s ready when you need it. This way, you won’t be waiting around after you’ve assembled the casserole. I like using this oven thermometer to ensure my oven is actually at the right temperature for even baking.
Blanch the Broccoli
Bring a large pot of salted water to a boil and add your broccoli florets. Let them cook for 4 to 5 minutes until they’re tender but still bright green.
You want them cooked enough that they’re not crunchy, but not so soft that they turn mushy in the oven. Drain them well and set aside.
Brown the Mushrooms and Garlic
Heat your olive oil in a large skillet over medium heat. Throw in the sliced mushrooms and let them cook undisturbed for a few minutes, allowing them to release their moisture and begin browning.
Stir occasionally and cook for 6 to 7 minutes total until they’re deeply golden. Toss in the minced garlic and cook for an additional minute until fragrant. A garlic press makes quick work of mincing garlic without getting your hands smelly.
Make the Creamy Sauce
Sprinkle the flour over the browned mushrooms and fold everything together so the flour coats the mushrooms evenly. This creates your roux.
Gradually whisk in the vegetable broth and plant-based milk, ensuring you scrape up any browned bits from the bottom of the pan. Add the nutritional yeast, soy sauce, onion powder, salt, and black pepper, then let it simmer for 5 to 7 minutes, stirring occasionally.
You’ll see it thicken into a creamy, pourable sauce.
Assemble the Casserole
Spread your blanched broccoli evenly in a casserole dish. Pour the mushroom sauce over the top and gently stir to ensure everything’s coated.
The sauce should settle into all the nooks between the florets. I always grab this baking dish because it doesn’t stick, and it cleans up easily.
Bake Until Bubbly
Pop the casserole into your preheated oven at 375°F and bake for 20 minutes. You’ll know it’s ready when the edges are bubbling and the whole thing is heated through. The sauce will thicken up even more as it bakes.
Add the Crispy Topping and Serve
Pull the casserole out of the oven and sprinkle the crispy fried onions evenly over the top. You can use store-bought or make your own.
The contrast between the creamy casserole and the crunchy onions is what makes this dish so addictive. Serve it warm straight from the oven. Enjoy!
If you’re transporting this to a potluck or gathering, an insulated casserole carrier like this one keeps it hot for hours and prevents spills in the car.
Equipment
Ingredients
- 1 pound fresh broccoli florets trimmed
- 2 tablespoons olive oil
- 8 ounces mushrooms sliced
- 3 cloves garlic minced
- 2 tablespoons all-purpose flour
- 1 cup vegetable broth
- 1 cup unsweetened plant-based milk
- 2 tablespoons nutritional yeast
- 1 tablespoon soy sauce
- 1 teaspoon onion powder
- Salt and black pepper to taste
- 1 ½ cups crispy fried onions store-bought or homemade
Video
Instructions
- Bring a large pot of salted water to a boil. Add the broccoli florets and cook for 4 to 5 minutes, until just tender. Drain and set aside.1 pound fresh broccoli florets
- Heat olive oil in a large skillet over medium heat. Add the sliced mushrooms and cook for 6 to 7 minutes, until browned. Stir in the minced garlic and cook for another 1 minute.2 tablespoons olive oil, 8 ounces mushrooms, 3 cloves garlic
- Sprinkle the flour over the mushrooms and stir well to coat. Gradually whisk in the vegetable broth and plant-based milk until smooth.2 tablespoons all-purpose flour, 1 cup vegetable broth, 1 cup unsweetened plant-based milk
- Add the nutritional yeast, soy sauce, onion powder, salt, and black pepper. Simmer for 5 to 7 minutes, stirring occasionally, until the sauce thickens.2 tablespoons nutritional yeast, 1 tablespoon soy sauce, 1 teaspoon onion powder, Salt and black pepper
- Spread the blanched broccoli evenly in a casserole dish. Pour the mushroom sauce over the top and stir gently to combine.
- Bake in a preheated oven at 375°F (190°C) for 20 minutes, or until hot and bubbly.
- Remove from the oven and top with crispy fried onions. Serve warm.1 ½ cups crispy fried onions
Notes
- Don’t skip blanching: Blanching the broccoli first ensures it’s tender throughout and keeps it bright green, rather than turning dull olive in color, which often happens when raw broccoli is overcooked.
- Brown the mushrooms properly: Let them sit undisturbed for a few minutes at a time, allowing them to caramelize instead of steaming. You want deep golden edges for maximum flavor.
- Whisk constantly when adding liquid: Pour the broth and milk gradually while whisking to avoid lumps in your sauce. If you dump it all in at once, the flour can clump up.
- Adjust the thickness: If your sauce seems too thick, add a splash more plant-based milk. If it’s too thin, let it simmer an extra few minutes before assembling the casserole.
- Add onions at the end: Wait until after baking to add the crispy onions. If you put them on before baking, they’ll get soggy instead of staying crunchy.
- Storage instructions: If you’re freezing individual portions, first freeze them uncovered on a baking sheet for 1 hour, then transfer them to containers to prevent them from sticking together and to easily grab just what you need.
Nutrition
How to Store Leftovers
This casserole keeps well, making it perfect for meal prep or serving ahead at gatherings. Let it cool completely, then transfer it to an airtight container and store it in the fridge for up to 4 days. I use an airtight glass container because it seals tightly and allows you to see what’s inside.
Reheat individual portions in the microwave for 1-2 minutes, or warm the entire dish in a 350°F oven for approximately 15 minutes, until heated through. The crispy onions might soften slightly after storage, so you can add fresh ones on top before reheating to regain that crunch.
For longer storage, you can freeze the casserole for up to 3 months. I recommend freezing it before adding the crispy onions to prevent them from getting soggy. Wrap the dish tightly in plastic wrap, then cover with aluminum foil, or divide it into portions using containers.
Thaw overnight in the fridge before reheating, then add fresh crispy onions right before serving.
What to Serve With Vegan Broccoli Casserole
This casserole works as a side dish for dinners alongside lentil loaf or baked tofu. It’s also hearty enough to serve as the main dish with a simple green salad and crusty bread. I love pairing it with roasted sweet potatoes, dinner rolls, cranberry sauce, steamed green beans, or glazed carrots for a complete holiday spread.
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