Crispy, crunchy hash brown patties made into a breakfast casserole! This delicious spinach mushroom cheddar hash brown casserole is loaded with tender veggies, melted cheddar cheese, and crispy hash brown patties. Perfect for serving for brunch on holidays!

cheddar hash brown casserole in baking dish

Behold, the easy make-ahead cheddar hash brown casserole that could feed a crowd without breaking a sweat! How perfect would it be for Easter, Mothers Day, Thanksgiving, Christmas, and every get-together that involves brunch in between?

This spinach mushroom cheddar hash brown casserole has gotten me out of more than one sticky situation! I’ve served it up at an impromptu brunch when I needed to use humble refrigerator and freezer ingredients and make something a little more elevated than scrambled eggs and hash brown patties.

But the best part about this recipe is that if you also keep a stash of hash brown patties in the freezer, you can put this casserole together in no time. I prefer the vegetarian version (I’m not a big breakfast meat-eater), but you could certainly swap them for meat too! More on that in a sec.

cheddar hash brown casserole slice on spatula

What ingredients do you need for spinach mushroom hash brown casserole?

  • Mushrooms: I like to use baby Bella mushrooms for this recipe as I find they have a bit more flavor than regular button mushrooms, but you could also use shiitake or a combination of mushrooms to make it the star of the breakfast casserole!
  • Baby spinach: baby spinach is a go-to for breakfast for me. I saute up a couple of handfuls before adding them to this casserole. Feel free to use kale or a mix of greens if that’s what you usually have on hand.
  • Minced garlic: just a hint of minced garlic helps flavor the casserole
  • Eggs: kind of a given when it comes to an egg bake like this one! I like to season the eggs so that the casserole is flavorful from the get-go!
  • Hot sauce: is a staple when it comes to my homemade breakfast casseroles! You can omit it from the ingredients if you don’t want the casserole to have any heat, or use anywhere from 2-4 tablespoons, depending on preference. My sweet spot is 3 tablespoons, and it gives the casserole a nice punch of flavor!
  • Hash brown patties: I use frozen hash brown patties from the freezer section of my grocery store. The best part is, you don’t have to defrost them for this recipe at all. And if you want them to be extra crunchy, give them a head start in the air fryer/oven before adding them to the casserole—more on that below.
  • Grated cheese: I’ve tried loads of different cheeses for this casserole, and you can make it as fancy as you like! Swiss works well, gruyere is phenomenal and makes this casserole posher, and cheddar is a classic. You can use a combination of cheeses or just one type!
sautéed mushrooms in pan
casserole layered before baking in pan

How to make a mushroom cheddar hash brown casserole that feeds a crowd:

  1. Prep all the things. Get your oven going so that it heats up by the time you’ve assembled the casserole. In a large skillet, add a drizzle of oil and cook the mushrooms until golden brown on both sides. Season them with minced garlic and a small pinch of salt, then remove them to a plate. You want to add another small drizzle of oil if the skillet is dry, add the spinach, cook until it wilts, season the spinach, and then remove it to the same plate as the mushrooms. In a large measuring cup, beat the eggs, hot sauce, salt, and pepper together until combined.
  2. Assemble the casserole. Spray a 9×13 baking dish with cooking spray. Add the sautéed veggies to the bottom of the dish. Pour the egg mixture over the veggies, sprinkle the cheese on top, and arrange the has browns in the dish. I like to let them overlap in the center so that they stand up a bit and don’t sink to the bottom.
  3. Bake the casserole. Bake the casserole until the hash brown are browned and the egg mixture is set. You can test this with a meat thermometer to make sure they’re done. It should read 165ºF. 
layered casserole in pan on white marble with towel

FAQs about cheddar hash brown casserole:

  1. Will the hash brown be crispy? They are crispy where they stand tall. To help the crisp factor, I personally like to give them a head start in the air fryer (you can also do this in the oven) before preparing the casserole.
  2. What else can I swap the veggies for? You can swap the spinach for sausage and peppers (another classic!) I suggest using about a pound of sausage, cook, crumble, and drain it before adding it to the casserole. You can saute the peppers if you like or just add them in; your call! You can also use turkey, chicken, or meatless sausage links/patties, cook them in the pan, slice them or chop them into tiny pieces before adding them to the casserole!
  3. How can I make this hash brown casserole ahead of time? You can prep the veggies, pack them up in an air-tight container and mix your egg batter as well, cover and refrigerate. When you’re ready to make the casserole, layer it all in the dish and bake.
  4. How do you suggest heating leftovers? I like to reheat leftovers in the air fryer at 250ºF for 6-10 minutes or until the sliced casserole is no longer cold in the center. You can also do this in the oven. Keep in mind the heating time will depend on how large the slices are.
cheddar hash brown casserole in dish on white marble

If you like this brunch recipe, you might also like:

broke piece of casserole on plate with fork
Yield: ~10 servings

Sautéed Spinach Mushroom Cheddar Hash Brown Casserole

Prep Time 15 minutes
Cook Time 30 minutes
Total Time 45 minutes

Crispy, crunchy hash brown patties made into a breakfast casserole! This delicious spinach mushroom cheddar hash brown casserole is loaded with tender veggies, melted cheddar cheese, and crispy hash brown patties. Perfect for serving for brunch on holidays!

Sautéed Spinach Mushroom Cheddar Hash Brown Casserole

Ingredients

  • 2 tablespoons oil
  • 10-12 baby Bella mushrooms, sliced
  • 2 teaspoons minced garlic
  • 2 cups packed baby spinach, roughly chopped
  • 10 eggs
  • 2-4 tablespoons hot sauce
  • 8 frozen hash brown patties (or use 2 heaping cups of tots)
  • Salt and pepper
  • 1 ½ cups grated cheese (gruyere, cheddar, or other cheese that melts well!)

Instructions

    1. PREP: Position a rack in the center of the oven and preheat the oven to 375ºF. In a large nonstick skillet over medium heat, heat a tablespoon of oil. When warm, add the mushrooms and saute them for 4 minutes or until they are golden brown. Season with minced garlic and a pinch of salt and let cook for 1 minute. Remove the mushrooms to a plate. Add the remaining oil to the skillet, add the baby spinach and allow it to wilt. Season with a small pinch of salt, and remove to the same plate as the mushrooms. In an 8 cup measuring cup, whisk together the eggs, hot sauce, and ½ teaspoon of salt, and ¼ teaspoon black pepper.
    2. ASSEMBLE: Generously spray a 9x13 baking dish (or similar) with cooking spray. Add the sautéed veggies to the bottom of the dish, pour the prepared egg mixture on top, sprinkle with the cheese. Arrange the hash browns in the dish; I like to overlap the corners in the center of the dish so that the hash browns stand up a bit and don’t sink to the bottom.
    3. BAKE: Bake the casserole for 30-40 minutes or until hash browns are browned on top and the egg mixture is completely set (you can test it with a meat thermometer to make sure, it should register at 165ºF.) Keep in mind, if you use the note to give the hash browns a head start, your casserole will be done a few minutes earlier than the times listed. Let cool for several minutes before serving.

Notes

    • If you want the hash browns to be extra crispy, I like to give them a head start in the air fryer - completely optional but it does make the potato texture crispier! Cook them in the air fryer for 375ºF for 6-7 minutes or in the oven (or a wire rack placed on a baking sheet.)
    • MAKE AHEAD: You can prepare everything in step #1 wrap the veggies or store them in an air-tight container a day in advance. You can also prepare the egg mixture and store it covered. When ready to prepare, just assemble the casserole.

Have you made this recipe?

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