Vegetarian Hash Brown Breakfast Casserole
Published Dec 16, 2022, Updated Nov 21, 2023
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This vegetarian hash brown breakfast casserole is loaded with vegetables and cheesy goodness and has a hash brown crust. It’s the perfect healthy breakfast dish to serve a crowd.
Christmas is right around the corner and if you’re planning an epic brunch spread, I have the perfect dish for you: hash brown breakfast casserole!
I love my sausage egg casserole, but I wanted to create a vegetarian egg casserole and if I do say so myself, this one hits the spot! It’s packed with loads of veggies and cheesy goodness and has the most delicious crispy hash brown crust.
Why You’ll Love This Recipe
- Jam-packed with lots of veggies and cheesy goodness!
- Fancy enough for a holiday breakfast, but also simple enough to make on Sunday as part of your weekly meal prep.
- Totally customizable… feel free to swap the veggies or cheese or add meat.
- Feeds a crowd and can easily be made in advance.
- Gluten-free + vegetarian.
- shredded hash browns – I’ve made this casserole with both frozen shredded hash browns and freshly shredded hash browns and I preferred the version with the frozen hash browns. It was easier and the crust crisped up better when cooking. If you go the route of shredding your own potatoes, I recommend using russet potatoes and using a paper towel to remove as much of the moisture in the potatoes as possible to prevent the crust from being soft and soggy.
- olive oil – helps the hash browns to crisp up while baking and for sautéing and veggies. Avocado oil is a great substitute.
- veggies – I used a combo of sautéed peppers, onions, garlic, mushrooms and spinach for the veggies, but feel free to use whatever veggies you have on hand! Broccoli, kale and/or zucchini would all be great veggie options.
- eggs – can’t have a breakfast casserole without eggs! I used 10 full eggs for this recipe, but feel free to do half liquid egg whites if you want to lighten this dish up a bit.
- non-dairy milk – any milk (dairy or non-dairy) will work, but I love using almond milk to keep things light. Store-bought or homemade almond milk will work. Just make sure you’re using unsweetened almond milk!
- salt & pepper – gotta have these two for flavor!
- cheddar cheese – adds some saltiness and creaminess to this dish! I used a block of organic sharp cheddar cheese and shredded it myself, which I highly recommend! If you need this dish to be dairy-free you can skip the cheese or use a dairy-free option. Nutritional yeast would also be a nice addition for some cheesy flavor without the cheese!
How to Make
Bake hash browns: Preheat the oven to 400°F and spray a 9×13 casserole dish with cooking spray. Add shredded potatoes to the baking dish and drizzle with 1 teaspoon oil and sprinkle with a dash of salt and pepper. Bake for 30 minutes, until potatoes start to brown and crisp up. Once you pull potatoes from the oven, press down with a spatula to help form the bottom crust more.
Sauté veggies: While potatoes bake, add 2 teaspoons of oil to a large skillet over medium heat and add onion, garlic, bell pepper and mushrooms. Cook for 7-10 minutes or until all the liquid from the mushrooms have evaporated. Add spinach with salt and pepper and stir until wilted. Once ready, take off heat and set aside to cool.
Combine: Whisk eggs and milk together in a large bowl. Once the veggies are cool, add them to the egg mixture with the cheddar cheese. Stir to combine, and pour the entire mixture into the baking dish on top of the hash browns.
Bake: Top off with an additional ½ cup of cheddar cheese and bake for 20-25 minutes until set and eggs are no longer jiggly. Let stand for 5 minutes, serve and enjoy!
How to Know When an Egg Casserole is Done
The good thing about this breakfast casserole is that you pre-cook almost all of the ingredients before baking the final product. The only thing that really needs to cook in the oven are the eggs! You do want to make sure the eggs are fully cooked and there are a few ways to check that:
- Eyeball it. The least precise of the three… obviously. The eggs will be set in the center aka no longer jiggly. Again, very official way of knowing, but I actually use this method a lot!
- Insert a knife into the center. If the knife comes out clean, that means the eggs are fully cooked through! If it comes out a little goopy, the eggs need to cook longer. Always check in the center of the casserole because the dish will bake from the outside > in.
- Use a thermometer. The most precise method to knowing if the casserole is done! Insert the thermometer in the center of the casserole – if it reads 160ºF or above, your casserole is done!
- For the best results use frozen, pre-shredded hash browns. This will result in a more crispy crust!
- Make sure to press the hash browns down with a spatula or spoon immediately after removing them from the oven. This will help to form the crust more.
- Make sure veggies have had time to cool off before adding them to the eggs, otherwise your eggs will start to cook!
- Skip the pre-shredded cheese and use hand-shredded cheese! I definitely recommend buying a block of cheese and grating it yourself. Fresh is always better and shredding the cheese takes no time at all. The pre-shredded store-bought cheeses typically contain preservatives like potato starch, natamycin and/or cellulose to prevent the shreds from clumping together in the bag. This will prevent your cheese from melting properly and will likely lead to more of a grainy taste/texture.
- If you’re short on time you don’t necessarily have to sauté the veggies, but I like the extra flavor it adds and the veggies are a bit softer.
- When sautéing the veggies, the mushrooms will release moisture, so make sure to cook them until the excess liquid has evaporated otherwise you could end up with a soggy casserole.
What to Serve With Hash Brown Casserole
This hash brown breakfast casserole would be such a great brunch addition! Here are some foods that would pair well with this dish:
- Fluffy Cinnamon Rolls or Vegan Coffee Cake – I love serving both sweet and savory options at brunch!
- Easy Fruit Salad – you can’t have brunch without a little fruit, right?!
- Peanut Butter Green Smoothie or Green Detox Smoothie – can’t go wrong with a smoothie at brunch!
- Whipped Coffee or Pumpkin Spice Latte – coffee is a must for brunch!
- Mimosas or Bellinis – if you’re looking to make this a boozy brunch, these are my two go-to drinks!
How to Make Ahead
This type of casserole is a great option for a holiday breakfast and it can easily be made ahead of time if you don’t want to bother with cooking the morning of. I recommend baking the full casserole the day before and storing it in the fridge. The next morning simply remove from the fridge, preheat your oven to 350°F and cook for 20-25 minutes or until casserole is warm throughout. Be sure to let the dish sit out of the fridge for a few minutes before putting it in the warm oven, otherwise your dish could crack.
How to Store + Reheat Leftovers
If you have leftover casserole, here’s how I recommend storing and reheating it.
In the fridge: After allowing the breakfast casserole to cool completely, cover and store leftovers in the refrigerator for up to five days.
In the freezer: Let the casserole cool completely then potion it out into individual pieces and store in the freezer for up to 3 months.
To reheat: You can either use the microwave, oven or toaster oven to reheat the casserole. I prefer the microwave or toaster oven for individual pieces and the oven for reheating the entire casserole. See my note above for instructions for reheating the whole casserole in the oven. If reheating from frozen, let the casserole thaw in the fridge overnight before reheating.
More Egg Recipes
- Healthy Breakfast Casserole
- Kale and Feta Crustless Quiche
- Dairy-Free Spinach Quiche
- Sausage Egg Casserole with Veggies
- Egg White Omelette
- Egg White Bites (Starbucks Copycat)
- Baked Egg Muffins
- Roasted Sweet Potato Kale Frittata
- Make-Ahead Breakfast Casserole
Popular Breakfast Recipes
- Apple Cinnamon Baked Oatmeal
- Almond Flour Waffles
- Gingerbread Baked Oatmeal
- Apple Dutch Baby
- French Toast Bake
- Fluffy Cinnamon Rolls
- Vegan Coffee Cake
- Morning Glory Muffins
- Almond Flour Pancakes
- Pumpkin French Toast Casserole
Hash Brown Breakfast Casserole
- 1 20 oz bag frozen shredded hash browns, about 4-5 cups
- 3 teaspoons olive or avocado oil, divided
- 1 cup yellow onion, chopped
- 2 cloves garlic, minced
- 1 red bell pepper, chopped
- 1 8 oz package mushrooms, chopped
- 1 5 oz bag of baby spinach
- 1 teaspoon salt, plus more to taste
- ½ teaspoon ground black pepper, plus more to taste
- 10 eggs
- ½ cup non-dairy milk, I used unsweetened almond milk
- 1 ½ cups shredded sharp cheddar cheese
- Preheat oven to 400°F and spray a 9×13 baking dish with cooking spray.
- Add frozen shredded hash browns (no need to thaw) to baking dish and drizzle with 1 teaspoon oil and a dash of salt and pepper. Bake for about 30 minutes until potatoes start to brown and crisp up. Once you pull potatoes from the oven, press down with a spatula to help form the bottom crust more.
- While potatoes are baking add 2 teaspoons oil to a large skillet over medium-high heat. Once hot, add onion, garlic, bell pepper and mushrooms. Cook until onions are translucent and all the liquid from the mushrooms has evaporated, about 7-10 minutes.
- Add spinach, salt and pepper to the mixture and stir until spinach has wilted.
- Once veggies are cooked, take off heat and set aside to cool.
- Whisk eggs and milk in a large bowl.
- Once veggies have cooled and are no longer hot, add to egg mixture along with 1 cup shredded cheese and stir to combine.
- Pour egg mixture into the baking dish on top of the hash browns and top with additional 1/2 cup of cheddar cheese.
- Bake for 20-25 minutes until set and eggs are no longer jiggly.
- Let stand for 5 minutes and serve.
Nutrition information is automatically calculated, so should only be used as an approximation.