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  • Makes one 3-quart casserole
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This flavorful veggie casserole uses portobello mushrooms to create a delicious, meaty filling that’s brimming with savory umami flavors. Juicy peas and tender carrots add tantalizing texture, while the velvety mashed potato topping gets its creamy consistency from plant-based milk and starchy potato water. Fresh thyme and smoky paprika infuse the saucy filling with all the cozy flavor you’d expect from comfort food, just minus the unhealthy ingredients. Pop this casserole in the oven until golden brown and scoop out a steaming serving when you’re craving a warm meal to satisfy your stomach and your soul. 

Tip: To make this meal extra hearty, you can substitute 2½ cups cooked lentils for the mushrooms.

From straightupfood.com

For more cozy vegan casseroles, check out these tasty ideas:

By Cathy Fisher,


  • 3 lb. russet potatoes, peeled and cut into chunks
  • 2 teaspoons granulated onion
  • 1 teaspoon granulated garlic
  • 4 cups chopped portobello mushrooms
  • 2 cups chopped onions
  • 1 cup chopped carrots
  • 1 cup chopped celery
  • 3 cloves garlic, minced
  • 3 tablespoons tomato paste
  • 1 tablespoon finely chopped fresh thyme
  • 2 teaspoon paprika
  • 2 cups green peas
  • 1 to 2 cups unsweetened, unflavored plant-based milk
  • Freshly ground black pepper, to taste


  • Preheat oven to 375°F. In a large pot combine potatoes, granulated onion, granulated garlic, and enough water to cover. Bring mixture to boiling; reduce heat slightly. Simmer, uncovered, 10 to 15 minutes or until potatoes are tender.
  • Meanwhile, in a large skillet cook mushrooms, onions, carrots, and celery over medium-high 3 to 5 minutes or until onions are golden, stirring frequently and adding water, 1 to 2 tablespoons at a time, as needed to prevent sticking. Add minced garlic; cook and stir 1 minute. Stir in tomato paste, thyme, paprika, and 1½ cups water. Reduce heat to medium-low. Cover and cook 10 to 15 minutes or until carrots are tender. Stir in peas. Remove from heat.
  • Drain and reserve cooking water from potatoes. Transfer potatoes to a medium bowl. Mash potatoes, gradually adding milk (or potato-cooking water, or a combination of the two) until potatoes are the desired consistency.
  • Stir 1 cup of the mashed potatoes into vegetable mixture in skillet. Spread mixture in a 3-quart baking dish. (The mixture should be like a thick stew but not watery. Spoon out any extra liquid.) Spread the remaining mashed potatoes over top. Drag a large serving fork or other utensil over the surface of the potato layer to create a textured pattern.
  • Bake 25 to 30 minutes or until lightly browned. Let stand 10 minutes before serving. Season with pepper.

Comments (3)

(5 from 2 votes)

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Made this for Thanksgiving with yukon gold potatoes instead of russet - so good!!


The picture of this dish shows a red diced vegetable in the mix as well as carrots, peas, etc. I don't see a red diced vegetable in the ingredients listed on the recipe. Could you clarify? Thanks


I think those are carrots

About the Author

Headshot of Cathy Fisher

About the Author

Cathy Fisher

Cathy Fisher is the creator of StraightUpFood.com, a website offering free recipes and information on eating a whole-food, plant-based diet free of salt, oil, and sugar. She is also a cooking instructor, teaching classes at TrueNorth Health Center and the McDougall Program, both in Santa Rosa, CA. Cathy began eating a plant-based diet in 1999, and in 2016 published her first cookbook, Straight Up Food: Delicious and Easy Plant-based Cooking Without Salt, Oil or Sugar. Find her on Instagram and Facebook.
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