Vegetarian Hash Brown Breakfast Casserole

4.99 43 Published Dec 16, 2022, Updated Mar 18, 2024 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.

Ingredients Needed

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:

Pro Tips

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, Almond Cake or Easy Berry 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 Baked Egg Muffins Roasted Sweet Potato Kale Frittata Make-Ahead Breakfast Casserole