Potato-Spinach Casserole with Trumpet Mushrooms

  • Prep-time: / Ready In:
  • Makes one 13×9-inch casserole
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A hint of black salt gives this scrumptious vegan casserole a quiche-like flavor profile, making it perfect to devour for either brunch or dinner. Hearty potato slices soak up the savory, herb-infused sauce, which is given an extra creamy boost with the help of shredded tofu. Earthy spinach and umami-rich trumpet mushrooms provide bursts of delicious flavor so each bite is full of complex textures and tastes. Perfect for tucking into on a cold night, the comforting combination of ingredients makes this recipe a keeper! Garnish with fresh chopped herbs or an extra dusting of nutritional yeast to really take it over the top.

For more vegan casserole recipes, check out these tasty ideas:

By Darshana Thacker Wendel,

Last Updated:


  • 2 lb. Yukon Gold potatoes, scrubbed and sliced into ⅛-inch- thick rounds (about 8 cups)
  • 2 cups chopped yellow onion
  • 2 cups chopped fresh trumpet mushrooms
  • 4 teaspoons garlic powder
  • 2 teaspoons dried thyme, crushed
  • 4 cups fresh or frozen spinach, chopped
  • Sea salt, to taste
  • Freshly ground black pepper, to taste
  • 7 oz. extra-firm tofu, drained and grated on the large holes of a box grater (1 cup)
  • 2¾ cups unsweetened, unflavored plant-based milk
  • ½ cups chickpea flour
  • 1 cup brown rice flour
  • ½ cup nutritional yeast
  • 1½ teaspoons baking powder
  • 1 teaspoon black salt or sea salt
  • ¼ teaspoon ground turmeric
  • ¼ teaspoon freshly ground black pepper


  • Preheat oven to 400°F. Bring a large pot of water to boiling. Add potatoes; boil 4 minutes to partially cook them. Drain; return potatoes to pot.
  • In an extra-large skillet cook onion, mushrooms, 2 teaspoons of the garlic powder, and the thyme over medium 10 minutes or until vegetables are just tender. (The mushrooms should release enough moisture to prevent vegetables from sticking.) Add spinach and season with sea salt and pepper; cook 2 minutes more.
  • Transfer half of the spinach mixture and half of the grated tofu to the pot with potatoes.
  • For sauce, in a blender combine the remaining eight ingredients and the remaining 2 teaspoons garlic powder. Cover and blend until smooth.
  • Add sauce to the pot with potatoes; stir to combine. Transfer mixture to a 13×9-inch baking dish. Spread the remaining spinach mixture and remaining tofu over the potato mixture. Cover with foil or an oven-safe lid.
  • Bake 20 minutes; uncover and bake 15 to 20 minutes more or until edges and top start to brown. Let stand 10 minutes before serving.

Comments (23)

(4 from 9 votes)

Recipe Rating

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David G.

*completely left out the 2 flours.

David G.

Didn’t have thyme so used Italian seasoning. Also substituted veggie broth for the nut milk, and doubled the tofu because I completely left out the w fours. Had to back it 45-50 minutes total but we loved it.


This recipe was so bad! OMG! The flavor was so bland even though I added extra salt and garlic. I do not recommend this recipe to anyone!

pam marx


Donelle West

Will russets work in this rather than Yukon? Thanks

Megan Edwards

Hi Donelle, Russet potatoes will work, but they won't be as silky or hold their shape as well as Yukon gold potatoes. Try looking for another waxy potato such as red potatoes or fingerling potatoes instead, which are lower in starch than russets and will cook similarly to Yukon golds. Let us know how it goes!

Alexandra T.

This is by far the worst ever recipe I have ever made. This sauce was not good at all. Would not ever make this again.


So disappointed - I love mushrooms and casseroles, but this was so bald, even after upping the garlic. Also- 4 minutes must not be enlightened to pre cook the potatoes, as they remained kinda hard. The only thing I changed (aside from upping the garlic) was whole wheat flour for rice flour, the rest was per recipe. I won’t be saving this one - so bummed.


Love this! I’ve made it twice. The first time I followed the recipe exactly and it was a little bland for me although my husband liked it. The second time I sautéed three carrots and three celery stalks along with the onions and mushrooms—added 1/2 tsp red pepper flakes to that mix as well. I also bought the black salt and used it in my second try too. The whole thing is just delicious, my husband pronounced it “company worthy”! That means our meat eating friends will like it too. We always serve our meat eating friends our favorite forks over knives recipes—many of the now do meatless Mondays with those same recipes. We keep feeding ‘em and hope to turn their Mondays into every day!


Oops, I forgot to add that I replaced the plant milk with veggie broth.


This recipe is really good! I added a twist to mine. When you cook the veggies add more mushrooms, onions and spinach (twice the amount) and 5 gloves 4-5 gloves of minced garlic (no garlic powder). The kind of mushroom doesn’t really matter I personally prefer black oyster for their consistency.


Could you do broth in lieu of the plant based milk?


I made this today with regular white button mushrooms. I didn't have brown rice flour but was able to grind some brown rice in my Vitamix. It turned out really well, albeit a little on the bland side. It makes a good base recipe that could easily be amended depending on what your taste dictates. I think I may try adding some shishito or jalapeno peppers to it along with some fennel seed next time.


Hello Donn Gross, How did your dinner turn out??


Recipe looks yummy...but trumpet mushrooms? Has anyone tried this with regular mushrooms that are easier to find and not so expensive?


You can use any mushrooms you want.


Where am i supposed to find something as obscure (expensive) as trumpet mushrooms? Alternatives???


I would just use any mushrooms you can get.


what can you use to replace the brown rice flour and the chickpea flour?

Judy Best

You can ground chickpeas in your Vitamix and it turns them into flour. I am going to look for rice flour today, so I will look in the Bob's Red Mill section of the grocery store.


Fresh and frozen spinach have very different volumes, is it really four cups of either? Also, is the brown rice flour just for thickening? Is there a good substitute? Thanks.

Donn Gross

I am using Oyster Mushrooms and did not include the tofu since I am allergic to Soy. I added some Cashew cream and used Arrowroot instead of Brown rice flour...It is in the oven and looking forward to a tasty dinner.


How was it?

About the Author

Headshot of Darshana Thacker

About the Author

Darshana Thacker Wendel

Darshana Thacker Wendel is a whole-food, plant-based chef and former culinary projects manager for Forks Over Knives. A graduate of the Natural Gourmet Institute, she is the author of Forks Over Knives: Flavor! She created the recipes for Forks Over Knives Family and was a lead recipe contributor to the New York Times bestseller The Forks Over Knives Plan. Her recipes have been published in The Prevent and Reverse Heart Disease Cookbook, Forks Over Knives—The Cookbook, Forks Over Knives: The Plant-Based Way to Health, and LA Yoga magazine online. Visit DarshanasKitchen.com and follow her on Instagram for more.
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