Vegan Broccoli Casserole Recipe

I turned the classic holiday broccoli casserole into a cruelty-free showstopper of silky cashew milk sauce, tender steamed broccoli, savory sautéed mushrooms and a crackling crown of crispy onions and breadcrumbs that will have everyone asking for seconds.

I am obsessed with this vegan broccoli casserole because it hits every texture I chase at Thanksgiving. Steamed broccoli florets stay bright and snappy, the kind that split under my fork.

And that cashew milk sauce, silky and nutty, wraps each bite without ever being saccharine. I adore the contrast when vibrant green meets creamy richness and a topping that shatters into crunchy bits.

I am not sentimental about sides, I just want honest food that demands seconds. This dish is proud, loud, and unapologetically moreish.

I bring it and watch plates empty. I eat the leftovers with zero shame.

Ingredients

• Broccoli florets: crunchy, bright green veggie that keeps the casserole fresh and hearty.
• Cremini or button mushrooms: earthy, meaty bite that makes it feel more substantial.
• Yellow onion: sweet base flavor, adds depth and cozy savory notes.
• Garlic: punchy aroma and a little heat that wakes the whole dish up.
• Raw cashews: creamy binder when blended, gives richness without dairy.
• Plant milk: thins the sauce naturally, keeps it silky and dairy-free.
• Vegetable broth: adds savory umami and prevents the sauce from tasting flat.
• Nutritional yeast: cheesy, nutty boost and a vegan source of B12-ish flavor.
• Flour or cornstarch: thickens the sauce so it clings to veggies nicely.
• Olive oil: light fruitiness and helps sautéing without overpowering flavors.
• Vegan butter: adds a buttery mouthfeel and helps the topping brown.
• Dijon mustard: tangy lift that cuts through the richness a bit.
• Soy sauce or tamari: deep salty umami, makes flavors feel more rounded.
• Lemon juice: bright acidity that keeps the casserole from feeling heavy.
• Kosher salt and black pepper: basic seasoning, essential for tasting everything.
• Smoked paprika: smoky warmth if you want a subtle extra layer.
• Panko or crushed crackers: crunchy, golden topping for satisfying texture contrast.
• Crispy fried onions or crackers: ultra-crunch finale and a nostalgic comfort touch.

Ingredient Quantities

• 1 1/2 to 2 lb broccoli florets
• 8 oz cremini or button mushrooms, sliced
• 1 medium yellow onion, diced
• 2 cloves garlic, minced
• 1 cup raw cashews, soaked and drained
• 1 cup unsweetened cashew or other plant milk
• 1 cup low sodium vegetable broth
• 1/4 cup nutritional yeast
• 2 tbsp all purpose flour (or 2 tbsp cornstarch for gluten free)
• 2 tbsp olive oil
• 2 tbsp vegan butter, melted-ish
• 1 tsp Dijon mustard
• 1 tsp soy sauce or tamari
• 1 tbsp lemon juice
• 1 to 1 1/2 tsp kosher salt, to taste
• 1/2 tsp freshly ground black pepper
• 1/2 tsp smoked paprika (optional but nice)
• 1 cup panko breadcrumbs or crushed crackers
• 1 cup crispy fried onions or another 1 cup crushed crackers for topping

How to Make this

1. Preheat oven to 375°F (190°C). Put a large pot of water to boil for the broccoli and line a 9×13 or similar baking dish with a little oil.

2. Soak 1 cup raw cashews in very hot water for 20 minutes if short on time, or in cold water for 4 hours, then drain. This makes the sauce creamy and not grainy.

3. Trim and cut 1 1/2 to 2 lb broccoli into bite sized florets. Steam or blanch in the boiling water for 3 to 4 minutes so they are bright green and just tender. Shock in ice water or run under cold water to stop cooking and drain well.

4. While broccoli cooks, heat 2 tbsp olive oil in a large skillet over medium high. Add 1 medium diced yellow onion and cook 5 to 7 minutes until soft and starting to brown. Add 8 oz sliced mushrooms and cook another 5 minutes until they give up liquid and it evaporates. Stir in 2 minced garlic cloves for 30 seconds until fragrant. Season with a pinch of salt and pepper.

5. Make the cashew sauce: in a blender combine drained cashews, 1 cup unsweetened cashew or other plant milk, 1 cup low sodium vegetable broth, 1/4 cup nutritional yeast, 2 tbsp flour (or 2 tbsp cornstarch for gluten free), 1 tsp Dijon mustard, 1 tsp soy sauce or tamari, 1 tbsp lemon juice, 1/2 to 1 1/2 tsp kosher salt to taste, 1/2 tsp black pepper and 1/2 tsp smoked paprika if using. Blend on high until perfectly smooth, scraping down sides. If using cornstarch, make sure it is fully dissolved.

6. Taste the sauce and adjust salt, lemon or mustard. If it feels too thin, pour it into a small saucepan and simmer gently for 3 to 5 minutes, whisking, until it slightly thickens. If you used flour, cook it a little so it loses the raw taste.

7. Combine the steamed broccoli and the mushroom-onion mixture in a large bowl. Pour the cashew sauce over and gently toss so everything is evenly coated. Transfer to your prepared baking dish.

8. Make the topping: mix 1 cup panko breadcrumbs or crushed crackers with 2 tbsp melted-ish vegan butter and a pinch of salt. You can stir in 1/2 cup of crushed crackers here if you want extra crunch. Sprinkle the breadcrumb mix evenly over the casserole, then scatter 1 cup crispy fried onions or another cup of crushed crackers on top for that classic crunchy finish.

9. Bake uncovered for 20 to 25 minutes, until the sauce is bubbly around the edges and the topping is golden brown. If the top browns too fast, tent with foil for the last few minutes.

10. Let rest 5 minutes before serving so the sauce firms up a bit. This is best made a few hours ahead and reheated at 350°F for 15 to 20 minutes. Leftovers keep well and actually taste better the next day.

Equipment Needed

1. Large pot (for boiling and blanching the broccoli)
2. 9×13 baking dish (or similar) lightly oiled
3. Large skillet (for onions and mushrooms)
4. Blender (high speed preferred for smooth cashew sauce)
5. Mixing bowl (big enough to toss broccoli and sauce)
6. Small saucepan (to thicken the sauce if needed)
7. Baking sheet or plate with ice water (for shocking broccoli)
8. Measuring cups and spoons, wooden spoon or spatula, chef’s knife and cutting board (you’ll use all of these, yes it’s a few things smooshed together)

FAQ

Vegan Broccoli Casserole Recipe Substitutions and Variations

• Broccoli: swap with cauliflower florets, or use green beans or frozen broccoli if fresh is hard to find. Cauliflower gives same texture, green beans give a firmer bite.
• Raw cashews: use silken tofu (same creaminess), or blanched almonds (soak first) or a cup of store bought vegan cream for a quicker crash.
• Unsweetened cashew milk: any unsweetened plant milk works, like oat or soy. For a richer sauce use lite coconut milk but it will add a slight coconut flavor.
• Panko breadcrumbs topping: try crushed potato chips, cornflakes, or gluten free breadcrumbs. For extra crunch you can mix in a handful of chopped nuts.

Pro Tips

1. Toast the breadcrumbs or crushed crackers in a dry skillet for 3 to 4 minutes before tossing with the melted vegan butter. It gives way more crunch and a nuttier flavor than just baking them on top. Watch closely though, they burn fast.

2. Don’t skip shocking the broccoli in ice water after blanching. It stops cooking and keeps the florets firm so the casserole doesn’t turn into mush. Pat them really dry with paper towels or a clean dish towel so the sauce sticks better.

3. If your cashew sauce seems grainy, blend longer and let it rest a few minutes before using. Also warm the liquid a bit before blending; it helps the cashews puree silkier. If it’s too thin, simmer gently to thicken, but stir constantly so it doesn’t stick.

4. Make the filling and sauce ahead and assemble just before baking. The flavors meld and it reheats beautifully. If you make it fully ahead, underbake by 5 minutes so it doesn’t get overcooked when reheating.