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Each slice of this easy egg breakfast casserole is thick, flavorful, and satisfying; plus, the recipe is an incredibly convenient breakfast choice since it’s make-ahead and infinitely adaptable. Like quiche, you can use your favorite seasonings and cheeses, vegetables like peppers and mushrooms, meats like sausage or bacon, or you can make it vegetarian. The best part is that you can assemble this dish ahead of time so breakfast is a breeze in the morning!

breakfast egg casserole with peppers, spinach, mushrooms, and cheese.

Breakfast casserole is an all-in-one hearty meal that can be made ahead of time, feeds a crowd, reheats well, and makes great leftovers. My family devours it. For all these reasons and more, I’ve made it nearly 100x (no exaggeration there) for breakfast, brunch, and, yes, dinner.

I originally published this recipe in 2015 and have simplified it over the years. Let me show you how it comes together so you too can experience this crowd-pleasing superhero meal.

This Easy Breakfast Casserole Is:

  • Adaptable to whatever vegetables, meats, cheeses, and herbs you have on hand.
  • Easy to make ahead of time.
  • Quick to throw together.
  • Great as a quick weekday meal or a lavish weekend or holiday brunch.
  • Excellent for entertaining a crowd.
  • Made with some bread to soak up moisture, but potatoes work too!
  • Ready for your favorite egg toppings like salsa, pico de gallo, green onion, cilantro, parsley, avocado, everything bagel seasoning, hot sauce, etc.
slice of egg and sausage breakfast casserole on green plate.

4 Main Components

When gathering ingredients for this recipe, I like to think of it as having 4 separate components. From there, you can have fun with variations.

  1. Vegetables
  2. Meat (or extra vegetables)
  3. Starch for soaking up moisture
  4. Egg, cheese, & milk mixture

Here Are the Endless Add-ins & Flavor Options

  1. Vegetables: Select which vegetables you’d like in the dish. Generally, the most popular with guests is bell peppers, spinach, and mushrooms. But I’ve also made this with broccoli/peppers, kale/mushrooms, and spinach/zucchini. Try to stick to 3–4 cups of vegetables total. Cook the vegetables down with some flavor-enhancing onion and garlic.
  2. Meat: Guests usually prefer meat in the casserole, so I add sausage. Or try using ground turkey, diced bacon, ground beef, or ground chicken. I usually purchase uncooked sausage for this and brown it with some dried rosemary or Italian seasoning to give it a little extra flavor, but that is optional. If the meat you’re using is pre-cooked, such as diced ham or shredded chicken, you can mix it with the cooked vegetable mixture before layering it into the dish.
  3. Starch: Like when making breakfast strata, sausage stuffing, and cream cheese French toast casserole, the bread should be slightly stale so it can soak up moisture. Crusty sourdough is FANTASTIC here. You can also use homemade artisan bread, a loaf of French bread, crusty baguette, biscuits, bagels or homemade bagels, or even day-old croissants (have you tried homemade croissants?!). To make it gluten free, use gluten-free bread or potatoes.
  4. Eggs, milk, & cheese: Whisk a dozen eggs with a little half-and-half or milk and stir in some shredded cheese. Like the vegetables and meat, use whatever cheeses you like best, such as sharp cheddar, pepper jack, feta, and/or smoked gouda.

Variations: One of my favorite variations of this recipe is everything bagel breakfast casserole. It’s a BIG HIT and consistently gets rave reviews. Or try my different method/recipe for biscuit breakfast casserole with homemade biscuits baked right on top.

eggs, half-and-half, spinach, garlic, sausage, cheese, peppers, and other ingredients.

Can I Use Potatoes?

Yes, you can replace the bread with diced hash brown potatoes—the kind you find in the freezer section of the grocery store. Guests have *loved* this version. Use about 3 cups (around 380g) of hash browns in place of the bread. You could also peel and dice fresh potatoes, but you’ll need to quickly cook them on the skillet for 10 minutes before using in this dish.

Do I Have to Use Bread?

Bread or potatoes, yes. Besides eggs, bread is the main ingredient. To avoid a spongey, wet dish, this breakfast casserole needs structure at the bottom. You see, when eggs bake, they release a lot of liquid. Chunks of crusty bread (or hash brown potatoes) soak up some liquid so the casserole is chunky and textured, not flat and wet. If you’re looking for something without this starchy addition, crustless vegetable quiche is a great option.

In Pictures: How to Make Breakfast Casserole

First, place the pieces of bread (or potatoes) in the bottom of a greased 9×13-inch or any 3–4-quart oven-safe dish. I usually use (affiliate links) this glass pan or the pictured red ruffled baking dish, which comes in a set with other sizes—definitely a splurge, but I’ve found the quality to be excellent. Showing you the bread scattered in the pan as well as the optional potato substitution:

chunks of bread and potatoes shown separately in bottom of red casserole dish.

Set that aside and pre-cook your vegetables and meat (if the meat is not cooked already). You can do this all in 1 big skillet on the stove, adding onion, garlic, and optional herbs like dried rosemary or your favorite seasoning blend. As that’s sizzling on the stove, whisk the eggs, milk, and cheese together:

Now it’s time to assemble, and I’ve made this process a lot easier over the years. Spoon all of the vegetables/meat mixture on top of the bread. Pour the egg mixture all over that:

Success Tip: Refrigerate Overnight

At this point, you can either bake it right away or refrigerate the casserole overnight and for up to 24 hours. During this time, the flavors mingle together and the bread has a chance to soak up some of the liquid and flavor. Wake up and all you have to do is slide it into the oven. If you’re in a rush, I do recommend at least 30 minutes in the refrigerator before baking, if you can spare it!

Bake until the edges are golden brown. Because it’s so egg heavy, the casserole puffs up in the oven like a cheesecake and then sinks back down as it cools. Cool for 5–10 minutes before slicing and serving.

overhead photo of egg and sausage breakfast casserole in red baking dish.
overhead photo of slice of egg breakfast casserole with spinach, sausage, cheese, and peppers.

What to Serve With Breakfast Casserole

For side dishes, fresh fruit and yogurt are light, simple, and quick. However, if you’re entertaining—or if you have several hungry teenagers in your house—pair this breakfast casserole with:

Your brunch guests will be beyond satisfied. Yes, even the teenagers!

Print
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breakfast egg casserole with peppers, spinach, mushrooms, and cheese.

Easy Make-Ahead Breakfast Casserole

  • Author: Sally
  • Prep Time: 20 minutes
  • Cook Time: 45 minutes
  • Total Time: 1 hour, 30 minutes
  • Yield: serves 12 1x
  • Category: Breakfast
  • Method: Cooking
  • Cuisine: American

Description

This easy breakfast casserole is infinitely adaptable and you can find variations and suggestions in the recipe Notes below. The version written below with sausage, mushrooms, bell peppers, spinach, and cheddar cheese is generally the most popular with guests. You can assemble the entire dish and refrigerate for up to 24 hours before baking.


Ingredients

Scale
  • 4 cups (175g or 6 oz) cubes of crusty bread*
  • 1 teaspoon olive oil
  • 1 pound ground pork sausage, casings removed*
  • 1 teaspoon dried rosemary or Italian seasoning, optional
  • 1/2 medium onion, diced (115g or 3/4 cup)
  • 2 garlic cloves, minced
  • 2 cups (275g or 910 oz) diced bell peppers
  • 1 cup (100g or 3 oz) sliced mushrooms
  • 1 cup roughly chopped fresh spinach
  • 12 large eggs
  • 1/4 teaspoon salt
  • 1/8 teaspoon freshly ground black pepper
  • 2/3 cup (160ml) milk or half-and-half*
  • 1 cup (100g or 3.5 oz.) shredded cheddar cheese
  • optional garnish: green onion and/or chopped parsley

Instructions

  1. Grease a 9×13-inch or any 3–4-quart oven-safe dish. Arrange bread cubes in an even layer in bottom of pan.
  2. Heat olive oil in a large skillet over medium heat. Add sausage and rosemary/Italian seasoning, if using, and break up the sausage into bite-size pieces with a wooden spoon or rubber spatula as it begins to cook. Add the onion, garlic, peppers, mushrooms, and spinach and cook until everything has slightly softened and sausage is mostly cooked through, about 5–6 minutes.
  3. Remove sausage and vegetable mixture from heat and spread in an even layer on top of bread.
  4. Whisk the eggs, salt, pepper, milk, and cheese together. Evenly pour over sausage/vegetable mixture. Add another sprinkle of salt and pepper on top.
  5. Cover casserole with plastic wrap or aluminum foil and refrigerate for at least 30 minutes and up to 24 hours. (When ready to bake, allow to sit at room temperature for 10–15 minutes as oven preheats.)
  6. Preheat the oven to 375°F (191°C). Bake the casserole, uncovered, until the top is golden, edges are crisp, and a toothpick inserted in the center comes out clean, about 40–45 minutes.
  7. Cool for 10 minutes, then slice and serve.
  8. Leftovers keep well in the refrigerator for up to 5 days. Reheat in the microwave to your liking.

Notes

  1. Make Ahead Instructions: This is an excellent make-ahead recipe because you can assemble it before baking up to 24 hours in advance. See step 5. You can also cook the sausage and vegetable mixture up to 24 hours in advance, cover and refrigerate until ready to use.
  2. Freezing & Reheating Instructions: To freeze, prepare and assemble through step 5, cover with plastic wrap, then a layer of aluminum foil, and freeze for up to 3 months. Thaw overnight in the refrigerator, and then bring to room temperature before baking as directed. You can also freeze the baked casserole for up to 3 months and when doing that, I suggest baking it in a disposable aluminum pan. Cool completely, cover with plastic wrap, then a layer of aluminum foil. When ready to eat, thaw it for about 24 hours (covered) in the refrigerator, remove the plastic wrap layer, then bake in a 350°F (177°C) oven for 25–30 minutes.
  3. Bread: Crusty sourdough is fantastic in this recipe, or use any crusty, hearty bread. The crustier or more stale, the better. If your bread is fresh and/or flimsy, cut into cubes and bake on a baking sheet in a 300°F (149°C) oven for 10 minutes. It’ll be slightly crisp and ready to use in this recipe. No need to wait for the bread to cool before layering into the baking dish.
  4. Using Potatoes Instead of Bread: You can replace the bread with diced hash brown potatoes—the kind you find in the freezer section of the grocery store. Use about 3 cups (around 380g) of frozen hash brown potatoes, no need to thaw. You could also peel and dice fresh potatoes, but you’ll need to quickly cook/brown them on a skillet with 1 Tablespoon olive oil over medium heat for 10 minutes before using.
  5. Sausage or Other Meat: If using pre-cooked sausage links or ham, cut into slices/chunks, and there is no need to cook either. Simply stir into the pre-cooked vegetables before layering into the dish. You can replace the sausage with ground turkey, beef, or chicken—simply pre-cook with the vegetables according to the instructions. If using bacon, I recommend reducing to 1/2 pound and cutting into bite-size pieces. Cook separately from the vegetables until browned. Drain, then mix with the vegetables before layering into the dish.
  6. Other Vegetables: Feel free to replace all or some of the bell peppers, mushrooms, and spinach with other vegetables such as chopped broccoli, sliced zucchini or squash, or kale. Pre-cook as directed.
  7. Vegetarian Option: You can leave out the meat and replace with another 1 cup of vegetables.
  8. Milk: For the richest, heartiest texture, I recommend half-and-half or whole milk. You can use lower-fat milk or dairy-free milk if desired.
  9. Cheese: I usually use a blend of regular and sharp white cheddar cheeses. Use whatever cheeses you like best, such as pepper jack, feta cheese, Swiss, and/or smoked gouda.
  10. Half Recipe: You can halve this recipe by halving all of the ingredients and using a 9×9-inch square pan. Bake time is slightly shorter, about 32–36 minutes.

Keywords: breakfast casserole, overnight breakfast casserole

Reader Questions and Reviews

  1. I made this today for a moms group and it was sooo good!!! Everyone enjoyed it and I will definitely be making it again soon! It had so much flavor, like all your recipes! Thanks for the hard work and great recipes!! I am making you French toast casserole for breakfast tomorrow. It is delicious as well!

  2. I just made the vegetarian version. I halved the recipe & used a deep pie dish. I also used rice milk. It was great!

  3. I just made the casserole it’s in the refrigerator looking forward to baking it in the oven tomorrow morning.   I’m bringing it into the office for our Thanksgiving breakfast 

  4. Sally, this looks delicious.  I’d love to make it for Christmas morning.  My daughter in law does not like ore eat cheese.  Any ideas?

  5. Thank you for a wonderful recipe! I’m a huge frittata fan, and typically make them using roasted vegetables, fresh herbs and whatever cheese and meat I have on hand. However, adding the bread layer takes it to an entirely new level – it’s like a beautiful, savory bread pudding, chewy and custard-like.. I loved being able to assemble it ahead of time and pop it into the oven to let it bake while I enjoyed coffee..

    I made this for Christmas morning brunch using roasted zucchini, cherry tomatoes, yellow, orange and red bell peppers, garlic and shallots, rosemary and tarragon with Gruyere, Parmesan and a little prosciutto. Everyone raved! Will be making this again and again..

  6. Made this for Christmas morning and it was a big hit. I couldn’t get enough, myself. Trying it again today. Saw another recipe where they cut up can biscuits, cut up on the bottom. Going to try it. Also didn’t make it ahead so I’m hoping it won’t be a problem. Love this recipe. Thanks for sharing and Happy Anniversary and New Year. 🙂

  7. Did you mention somewhere that this can be frozen AFTER it’s baked? I don’t have room for a baking pan in my freezer but I do have room for smaller portions after its baked.

    1. Yes, I’ve done it before! Simply let it thaw overnight in the fridge then heat in a 350 oven until warmed through. 20 minutes or so.

  8. I made this casserole last night. Let it sit in the fridge for two hours, omitted the meat and substituted an extra 8oz of mushrooms. It’s delicious!!! I will be reheating it in the oven so it can crisp up again. Awesome flavor.

  9. Hi Sally! I’m having company for breakfast on Saturday and know this will be a hit (as all of your recipes always are!) but wondered about timing.  Do you think I could assemble it on Friday morning, refrigerate until Saturday morning and then bake or would that be too long for it to sit?
    [I’m really just trying to sleep for as long as possible on Saturday morning 😉 ]

  10. Hi Sally- my daughter and I love your blog and recipes! Can this be eaten at room temp or is it better warm out of the oven? Thank you dally!

    1. I love it room temp– even cold sometimes! The flavor is best at room temp in my opinion.

  11. Made this for Easter brunch. I left out the sausage and added asparagus. It was super easy to make and so good!

  12. If I am making this to freeze divided into two 8×8 pans what should my cook time for them be once thawed?

  13. My husband calls this “breakfast fiesta” and insists I make it when we have company. My mom even asked me for the recipe. My mom… Asked me… How to make something. We leave out the mushrooms, and I swapped the yellow onions for chopped green onions, but, needless to say, this reside is a huge hit in my house. Thank you!!!

  14. This was SO easy and I enjoyed all the add-ins exactly as you recommended!  Love that I was able to just stick it in the oven in the morning.

  15. This is a magnificent recipe!!  I subbed bacon (cooked and crumbled into veggies after sautéing) and used 8 oz of shredded pepper jack vs 1/2 c.  My casserole dish was bigger than 13×9, so used 6 slices of gluten-free bread, cubed. Will absolutely make again!!

  16. Made this last night and had for dinner tonight. My hubby and I LOVED IT. We both had seconds. Will definitely be making again.

    1. I’ve made the casserole with several different kinds actually– italian sweet, mild italian, breakfast sausage, smoked sausage– it’s all so good! You can’t go wrong. Just use what you like best.

  17. I have made a breakfast casserole like this for year but always used seasoned croutons instead of bread; really makes it full of flavor. But if I need to make it without bread of any kind what can I use as a binder that would work like bread but without the carbs?

    1. Hi Deborah, you can simply leave the bread out in this particular casserole. The texture of the casserole will change, but it will still have wonderful flavor.

  18. Made this the day before Easter and it was a hit!! I let it cook a little bit longer as I added extra eggs and veggies and sausage, came out perfect. Thanks!

  19. Hello! If I wanted to serve this in two tart dishes should I just split the recipe in half? Or do 1.5 of the recipe? Any idea how long to bake?

    Thanks so much!

    1. Hi Stephanie! This breakfast casserole can easily be split in two for your tart pans. No need to 1.5x the recipe. Bake time will be shorter, but I’m unsure how long. Once the edges look set and the tops is lightly browned, the casseroles are done.

  20. Made this casserole yesterday for Christmas breakfast. I used sweet Italian sausage. It was a great big hit! Thank you so much for this wonderful recipe!

  21. I see you can freeze it- would you freeze raw egg? Or cook it first? Please advise! Thank you! Looks yummy and want to try it this weekend!

  22. Hi Sally!
    I am planning on making this in a 9×9 pan since it is just me eating it. Would you suggest halving the ingredients? And how long should it be cooked for?

    1. Hi Audrey! Yes, I recommend halving the ingredients for a 9×9 inch baking pan. I’d say about 30 minutes, but keep your eye on it. Enjoy!

  23. Looks Great Sally – i made a copy of the recipe. I made a 6 inch cake today and frosting and took a couple of pics tomorrow – because i just got my internet and land line phone working after 2+days! Anyway it seems solved. Will send pics to you – email, reply to this tomorrow – anything , Its not great but its not too bad. Was nervous trying to go with the butter, eggs, cream, sugar and my Daddio 6inch pans and have been reading so much on the room temperature, and all of your wonderful explanation of base and acid or the ingredients. At&t had a real block out here in Wi. Not too happy about that. Thanks again for all of your knowledge!

  24. I want to make this ahead of time and freeze for a trip. Do I have to use a glass baking dish or can I use an aluminum throw away pan.

  25. I was looking to make this for a breakfast potluck at work. Can this be made in muffin tins for single servings?

    1. I think the flavor would be delicious! I’m unsure of how the texture of the chips would hold up but will you please let me know if you try – it sounds great!

      1. Hi Sally

        I fried tortillas to a semi crisp, cut up and turned out great!

        Cheryl

    2. Hi Sally can I store this in the fridge for 2 nights then bake in the morning

      1. Hi Joan! We only recommend storing this in the fridge for up to one day before baking.

  26. Hi Sally!
    My mom and I are considering making this for breakfast on the morning after Thanksgiving, but we were kind of confused about the bread at the bottom. Is it like a crust? What is the texture of the bread like after baking?
    Thanks!

    1. Hi Ricki! It’s not a crust– it helps soak up the egg so the casserole isn’t flimsy and liquid-y. It has a chewier texture. Definitely try it– it’s 100x better with a little bread!

  27. Just wondering why you need to let the casserole come to groom temperature before baking? Could you not bake from fridge?
    Thank you.

    1. Hi Nancy! Placing a cold baking dish in a hot oven could warp it (or even shatter it). You can if you’d like to take that risk– sometimes I do with my ceramic pans– but it’s best to bring to room temperature first to avoid that possibility.

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