Cheesy mushroom spinach egg casserole is easy to make, great for a gluten-free breakfast casserole, and it’s meatless!
This spinach mushroom casserole has been making an appearance at our house for breakfast and brunch for nearly 30 years.
At first, it started out as a “strata” which had chunks of white bread.
After we started cutting back on gluten and bread in general, I figured out a way to omit it from this mushroom casserole recipe without affecting the taste.
The result, little did I know at the time, was a low-carb, spinach breakfast casserole. I now make this dish whenever we have guests staying over.
What’s in a Breakfast Casserole?
Every good breakfast casserole starts with a base of eggs. But from there you can add just about anything!
This egg spinach mushroom casserole version is vegetarian, but you can also add diced ham or sausage.
I make another casserole with just Hatch chiles, that mimics Chile Rellenos (but without the carbs), for those who like it spicy!
For the cheese, you can go crazy! Sharp cheddar is the perfect foil for casseroles with spinach, eggs, and mushrooms.
Asparagus Mushroom Crustless Quiche looks a little fancier if you are having just a few people over. It’s delicious for lunch as well.
Can I Make a Gluten-Free Breakfast Casserole Ahead of Time?
There are two ways you can make this casserole ahead of time.
First, you can prep the entire egg spinach casserole, cover it, and refrigerate it until the morning.
The other way is you can make and refrigerate it and then simply reheat it the next morning.
To re-heat, turn the oven to 325 degrees F. Put the covered casserole into the oven and heat until hot and bubbly, about 35 minutes.
If you’re doing meal prep and you’d rather have smaller portions, you can refer to this recipe for gluten-free egg “muffins”.
It’s a great way to make this spinach and mushroom recipe in muffin cups!
It gives adjusted cooking time and ingredient amounts. Feel free to use whatever vegetables and cheese you like.
Can You Freeze Breakfast Casseroles?
Yes! Just cut into individual portions and wrap well.
This is a great way to have a grab-and-go breakfast! Just defrost the night before in the refrigerator and heat until warm and bubbly in the microwave.
This spinach egg casserole will last about 6 months in the freezer.
How to Make Spinach, Egg, and Mushroom Casserole
Preheat the oven to 350* F. Use butter to grease a baking dish.
Heat 4 Tablespoons of butter in a large saute pan and sauté onions and mushrooms, then add garlic.
After another minute or two, add spinach, and let it wilt.
Drain excess water from the spinach mixture and chop finely.
In a separate bowl, whisk together the eggs, cheeses, green onions, and spices.
Add spinach and mushrooms to the egg mixture and mix well.
Pour into a baking dish and smooth. If planning on refrigerating to bake later, wrap well in foil. It is now ready to bake.
Bake for 45-50 minutes or until the top is golden brown and the center is done.
Add an additional 5-10 minutes to cooking time if baking from the refrigerator, and enjoy!
Some of the items used in this post are available at my Amazon Affiliate Store. As an Amazon Affiliate, I may earn a commission on qualifying purchases.
Spinach and Mushroom Breakfast Casserole
Ingredients
- 5 Tablespoons unsalted butter divided
- 1 medium onion chopped (about 7 ounces)
- 8 ounces mushrooms sliced
- 12 ounce baby spinach
- 2 cloves garlic minced
- 6 eggs beaten
- 16 oz. cottage cheese
- 12 ounces sharp cheddar cheese shredded
- 3 green onions sliced
- 1 teaspoon kosher salt
- 1/2 teaspoon black pepper
Instructions
- Pre-heat oven to 350* F. Use 1 Tablespoon butter to grease 13″ X 9″ baking dish.
- Heat 4 Tablespoons butter in a large skillet or sauté pan, and sauté yellow onions and mushrooms, about 3-4 of minutes until onions are translucent and mushrooms are soft. Add garlic and sauté another minute.
- Add spinach, a handful at a time, and sauté. Cover skillet and let spinach wilt, about 5 minutes.
- Let cool, drain excess liquid, and chop more finely.
- In a separate bowl, whisk eggs, cottage cheese, cheddar cheese, green onions, and salt and pepper. Add cooked spinach and mushroom mixture.
- Mix well and pour into baking dish.
- Bake for 45-50 minutes or until top is golden brown and center is done.
Notes
Nutrition
Sandy Loper says
Sounds wonderful and oh so easy!
Sandy Loper says
Made it! Loved it! And just finished off the leftovers! Thank you, a new dish for my Brunch/Breakfast line up! And sooo easy to follow. Good Job!
Cynthia says
Thanks sandy! What do you think of my new website?
Sandy Loper says
Love it! Keep up the good work!
Cynthia says
Still eating the left-overs!
Mom says
Wow, great website
Lynn Lewis says
Yeah hopefully you get my.comment! Thanks for making it easier for computer blockheads like me!! I love your site. Will finally try the 5 minute bread this year one of my new years resolutions!
Cynthia says
Yes, your comments worked! Yeah!
Ilene says
How delightful is this website???
Equally delicious is the food you prepare and serve.
What a joy to wake up and find another post by you.
Excellent job, Cyn!
Cynthia says
Thanks so much for your comments Ilene! Love you!
Vicki houghton says
This is a just. That’s sounds so good!!!!
Cynthia says
Easy too Vicki and friendly-ish on the waist since there’s no bread!
donna boaz says
Saw your mom over the weekend and she told me about your site. I love to cook and eat and getting would appreciate less time in the kitchen.
If you go back in time: I am a friend of Irene, Nessa’s sister, Donna.
I have the three children that you just might remember: Leslie, Miles and Hollye.
Leslie just moved into your neighborhood so expect her to call or email.
What a small world.
Donna Boaz
Cynthia says
Hi Donna! Thanks for visiting! I hope you like it. Yes, I remember you…well, at least from Nessa talking about you and your kids! It’s been years! Small world that your daughter lives so close to me. Yes, have her contact me. I am sure she went to the parade since were walking distance?
Christina Barnes says
Great recipe! Can’t wait to try it!
Cynthia says
Let me know how you like it!
Christina | Christina's Cucina says
I love that you’ve not only updated the photos, but the recipe! Looks wonderful and a great breakfast or brunch dish to look forward to!
Cynthia says
Thank you Christina!
Donna Pariseau says
This recipe calls for 5 T of Butter Divided.
Step 1 – use 1 T
Step 2 – use 4 T
However, Step 5 calls for butter and there would be none left.
How much butter are we using for Step 5?
Also, how would this recipe work making the night before?
Cynthia says
Hi Donna,
Sorry! You are correct…just 5 Tablespoons total. I’ve edited it to reflect the change.
Thank you!
Cynthia
Cathy says
Could this be made the night before? Then baked in the morning?
Cynthia says
Yes, I have assembled it the night before and baked it the next morning…Just make sure you put a sheet pan underneath it and wrap it well so it doesn’t spill in the fridge.
Stace says
How many days will this last in the fridge?
Or would it stay good if I froze it? It’s just me so wondering how to make it yet not have to eat it every day! Thanks!
Cynthia says
Sometimes I make it on Sunday and we’ll finish it up by thursday.
Vicky says
Looks beautiful and something I will need New years day to start the year out right.
MARIA says
Hello. Just wondering what the nutritional information is on this recipe? Specifically the fat/carbs/net carbs/sugar. Thank you!
Cynthia says
I know there are a lot of calculators that can figure out the nutritional information. Since I don’t believe in counting calories or dieting, I don’t keep track of that information.
Sam K says
Did you ever figure out the nutrition information on this? Its hard to count general macros when its not provided. Thanks!
Zee says
Have you ever substituted another cheese for the cheddar – or did a “half cheddar, half other?
Cynthia says
Zee, I make it so many different ways! I use broccoli and chilies with pepper jack cheese, feta, you name it! I do like a tangy cheese, just because it has more flavor. Swiss would be good too! Experiment with your favorite combos of veggies and cheese.
Kathryn says
Just wondering if this would work ok to split the recipe in half? Like an 8×8 dish…Just do a shorter bake time? This looks delicious!
SAra says
This has quickly become a family favorite of ours! I am sharing it with all of my friends. Thank you!!
Denise says
Can I use ricotta cheese instead of cottage cheese? part skim ricotta
Cynthia says
sure! probably would give it luscious richness!
Katy says
I love this!! I have made it about 5 times for dinner.Thank you!
Diana says
I made this last week for the first time, and my family and I loved it! I did change just a couple of things to use up what I already had at home – I used 6-7 oz. of fresh baby spinach, 2 (4 oz) cans of organic mushrooms sliced, 8 oz. of sharp cheddar and 4 oz. of mild cheddar. It turned out beautiful, and the flavor was out of this world! Thanks for a great recipe. This is definitely going into the rotation.
Cynthia says
awesome Diana! It’s a pretty flexible recipe. You can pretty much add any vegetables or cheeses. I’ve used canned chiles and pepper Jack.