Easy Make-Ahead Breakfast Casserole

This easy breakfast casserole is infinitely adaptable! Use your favorite seasonings, vegetables, meats, cheeses, or make it vegetarian. The best part is that you can prepare it ahead of time so breakfast is a breeze in the morning.

breakfast casserole in a glass baking dish

Today’s breakfast casserole recipe comes from my dear friend Kristen. She made it for us when we visited last month. As I gobbled it down, I couldn’t stop saying “I have to share this on my blog, I have to share this on my blog, I have share this on my blog.”

As it turns out, this is something Kristen makes on the regular. And I understand why! Besides taste, this breakfast casserole is pretty impressive in the health category. Full of protein, packed with vegetables. Not only that, it’s so easy to make and adaptable to whatever veggies, cheeses, meats, seasonings you love/have on hand. Confession. I’ve made this 4 times in 3 weeks.

breakfast casserole

↑ ↑ Soooo much texture and flavor!

This is a big breakfast casserole. I’m talking 12 huge servings, so it’s perfect for dinner or breakfast/lunch the next day. I reheat it in the microwave and top it with hot sauce. Delicious! I took a bunch of step-by-step photos so instead of displaying them all above the recipe, I included them below along with more detailed instructions for you.

Entertaining? If you’re entertaining, pair this breakfast casserole with slow cooker cinnamon rolls or my overnight cinnamon rolls. Both homemade and both VERY easy, especially if you’re a yeast beginner.

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breakfast casserole in a glass baking dish

Easy Make-Ahead Breakfast Casserole

  • Author: Sally
  • Prep Time: 8 hours, 35 minutes (overnight)
  • Cook Time: 40 minutes
  • Total Time: 9 hours, 20 minutes
  • Yield: serves 12
  • Category: Breakfast
  • Method: Cooking
  • Cuisine: American


This easy breakfast casserole is infinitely adaptable! Use your favorite seasonings, vegetables, meats, cheeses, or make it vegetarian. Makes excellent leftovers for breakfast, lunch, and dinner during the week! Make sure to read the recipe notes and check out all the step-by-step pictures below this recipe before you begin.


  • 3/4 pound uncooked sausage, casings removed*
  • optional: 1 teaspoon dried rosemary to give the sausage more flavor
  • 2 bell peppers, diced (any color you prefer; about 2 cups)
  • 1 cup sliced mushrooms
  • 1 cup fresh spinach
  • 1/2 medium yellow onion, diced
  • 1 teaspoon minced garlic
  • salt and fresh ground black pepper
  • 4 slices day-old bread (gluten free, whole wheat, white, sourdough, any kind you like)
  • 10 large eggs
  • 1/2 cup milk (I use almond milk, any milk works)
  • 1/2 cup shredded cheese*


  1. Set a large skillet over medium heat and coat it with nonstick spray or a drizzle of olive oil. Place sausage in the skillet and begin to break it up with a spatula or fork. Stir in the rosemary and brown the sausage, about 6-7 minutes.
  2. Meanwhile, set a 2nd skillet over medium heat and coat it with nonstick spray or a drizzle of olive oil. (If you have a skillet large enough to fit both the sausage and veggies, you can just add the veggies to the sausage that is browning in step 1.) Add the peppers, mushrooms, spinach, onion, garlic, and a sprinkle each of salt and pepper. Begin stirring and cooking the veggies down until tender, about 6-8 minutes.
  3. Set sausage and veggies aside.
  4. Generously grease a 9×13 baking pan. Break the bread into pieces and place in the pan in an even layer.
  5. In a large bowl, whisk the eggs, milk, and 1/4 cup shredded cheese together. Pour half of this egg mixture over the bread. Top with the sausage and vegetables, then the remaining egg mixture and remaining 1/4 cup cheese. Add a sprinkle of salt and pepper on top.
  6. Cover casserole with plastic wrap or aluminum foil and refrigerate for 2 hours or overnight– or up to 1 day. Allow it to come to room temperature before baking.
  7. 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. I like mine on the super crisp side, so I bake it for around 45-50 minutes. Allow to cool for 10 minutes, then slice and serve. Tastes awesome with hot sauce on top.
  8. Leftovers keep well in the refrigerator for up to 5 days. Reheat in the microwave to your liking.


  1. Make Ahead & Freezing Instructions: Obviously this is a make ahead recipe! However, you can brown the sausage and cook down the veggies up to 2 days in advance– simply put the two in a tupperware in the refrigerator until ready to use in the recipe. Also, you can freeze this breakfast casserole. Prepare through step 5, then cover the casserole with plastic wrap, then a layer of aluminum foil. Freeze for up to 3 months. Allow to thaw overnight in the refrigerator. Bring to room temperature, then continue with step 7.
  2. The onion, garlic, salt, pepper, and cheese are key to great flavor! Don’t leave them out.
  3. Sausage: Instead of sausage, try browning ground turkey, ground beef, or ground chicken instead. Or use ham. Or cooked shredded chicken.
  4. Vegetarian Option: You can leave out the meat. Just an extra cup (or so) of veggies in its place.
  5. Cheese: I usually use shredded pepper jack cheese– other varieties I love for this breakfast casserole are mozzarella, smoked gouda, swiss, and cheddar.
  6. Special Tools: Skillet | Glass Mixing Bowls | Whisk | Wooden Spoon | Glass 9×13 Baking Dish

Keywords: breakfast casserole, overnight breakfast casserole

How to Make Breakfast Casserole

Vegetables: Gather veggies like colorful peppers, mushrooms, and spinach. I’ve done this with broccoli/peppers, kale/mushrooms, and spinach/zucchini. Try to stick to 3-4 cups veggies total. Cook the veggies down with a little garlic, onion, salt, and pepper. Those last 4 ingredients are where all the flavor comes from.

sautéed vegetables in a skillet with a wood spoon

Meat: We like a little meat in the casserole, so I add sausage. Kristen usually uses turkey sausage, so go ahead and use that if you prefer. Instead of sausage, try using ground turkey, ground beef, or ground chicken instead. You can also use diced pre-cooked ham or cooked shredded chicken. You don’t need to pre-cook either of those options.

I brown the sausage with some rosemary to give a little flavor. You can cook down the veggies and brown the sausage in 1 giant skillet if that’s easier for you.

  • Vegetarians: You can leave out the meat. Just use some more veggies in its place!

cooked sausage and rosemary in a skillet with a wood spoon

Bread: Grab your favorite crusty bread and tear it into little pieces. The bread will be the bottom of the casserole. It soaks up some of the egg and gives the egg casserole texture. It is SO good! Otherwise, you’d just be eating a quiche of sorts. I’ve been using gluten free bread for my sandwiches lately, so if you don’t eat gluten, you can use your favorite GF variety. Or you can certainly use wheat, sourdough, white, rye, whatever. You’ll need about 4 slices of bread.

2 images of cubed bread and whisked eggs in a glass bowl

Eggs, milk, & cheese: Whisk the eggs with a little milk and cheese. Like the veggies and meat, use whatever cheese you like best. I’ve been using pepper jack cheese for its flavor but I’ve done everything from cheddar to smoked gouda and swiss. Half of the egg mixture goes on top of the bread, then sausage and veggies, then the remaining egg mixture.

Once the eggs are poured on top of it all, you can refrigerate the casserole overnight. Wake up and all you have to do is throw it in the oven. When we visited Kristen, the morning was totally no-fuss; all she did was brew some coffee and cut up fresh fruit as the casserole cooked. Enjoy!

pouring egg mixture into glass casserole dish filled with vegetables and sausage

overhead image of pieces of breakfast casserole on green and yellow plates with a fork


  1. Andrea | Cooking with a Wallflower says:

    This breakfast casserole looks so delicious. I love the vibrant colors and just how easy it is to make this. I can just imagine myself savoring this on the weekends and packing this for lunch to bring to work the following week. I’m so excited to give this a try!

    1. Anita Wallace says:

      This was delicious. I substituted diced ham for the sausage and leftover potatoes for the bread. Everyone loved it.

  2. Yum!! Can not wait to try.  I love to add an herby greek yogurt dip along with my stratas/casseroles. Sooo delicious…..and your pictures truly are amazing. The colors are so vibrant and just, wow!!

    1. I’m SO intrigued with the greek yogurt dip addition. Would work so well with these flavors!

      1. Would the greek yogurt be added in with the wet ingredients before baking or on the side when serving? 

  3. ioliascookbook says:

    Excellent breakfast (and not only) recipe. So colorful & tasty.

    IF I can recommend something, you can also add Feta cheese.

  4. Heather (Delicious Not Gorgeous) says:

    this veggie heavy strata/casserole sounds so tasty! and i find that protein-filled breakfasts keep me fuller than granola/toast/etc, so this will be perfect as i start getting busier this fall (:

  5. Anything you’ve made 4 times in 3 weeks sounds like a huge winner to me. I’m not a lazy guy, I just want good food on demand. Crisp edges are my favorite too. I should bring this is for my co-workers on that “bring a dish to pass” day coming up. Thanks!

  6. looks absolutely delicious!! yummy


  7. Linda @ Today She Loves says:

    This looks delicious and very fulfilling for a breakfast meal. 

  8. This casserole looks great! I barely have any time in the mornings currently to focus on food, so for me, making stuff ahead and cooking it as I have coffee, get dressed, etc, or just having a couple muffins that are easy to grab while I have coffee is the only way I stay sane in the morning. Definitely going to try this and definitely going to use zucchini! My favourite vegetable 🙂 

    1. Enjoy Hayley!

  9. My only issue is I don’t tend to like cooked vegetables. I mainly only like them fresh. But maybe this will change my mind, so I’ll have to give it a go!

  10. When I looked at the picture my first thoughts were HAPPY and SUNSHINE.  It is a perfect recipe bcause you don’t have to stick to a recipe 🙂 I have so much stuff from the garden in single units- 1 red bell pepper, 1 yellow, a little bit of swiss chard, etc.  This recipe is a perfect solution to use all of that.  Plus, it is a perfect meal choice on a rainy morning (with us moving further into the fall season). It will brighten your day right from the start.  Thanks Sally for sharing.

    1. It’s a bright and cheery (and convenient!) dish for sure Irina. A pan of sunshine. I like it!

  11. Perfect!  My aunt will be staying with us for a few days and I usually make something on the weekend when I have more time vs. weekday mornings….sounds like Sunday morning will be a treat!

  12. Love your savory recipes Sally and a make ahead breakfast casserole is even better. My husband and I do breakfast for dinner once every couple of weeks and this will be on the menu. Thanks so much!!

  13. Love a great make-ahead breakfast recipe!

  14. Wow, this dish is loaded with veggies and savory flavor – which I love!  And thank you for the great tips about making it ahead / freezing / saving for later; that’s perfect for when people are only cooking for 1 or 2 in their household, and can have breakfast prepped pretty much for the week with this sort of thing.  Love it!

    1. Exactly– there are only 2 of us BUT this recipe is perfect because of all the leftovers for later in the week or freezing. I love it.

  15. Karen @ On the Banks of Salt Creek says:

    I love make ahead breakfast casseroles. If I can put that in the oven before I head out to do barn chores my life is so much easier. This looks delightful.

  16. Looks great! A couple questions:
    Do you bake the casserole directly after removing it from the fridge or do you let it come to room temperature before placing it in the oven to decrease the chances of the glass shattering/cracking? If so, how long do you need to let it sit at room temperature for before you can bake it?
    Also, if you are making this vegetarian-friendly, how much extra vegetables would you recommend using in place of the meat? 

    1. Rella– two great questions. Yes, let it come to room temperature before baking if it has been in the fridge. Add another cup or so of veggies.

  17. As a savory-breakfast person myself, I’m always on a look out for variety of savory breakfasts. We can only take so much scrambled eggs, omelets and fried eggs, you know. Definitely adding this to my routine! Love the colors!

    1. Yeah! Enjoy Shinee!

  18. So looking forward to trying this recipe! A question for you though, in general, I worry about the dreaded soggy bread issue. I wanted to see if I could make this for my upcoming maternity leave to have on-hand in my freezer and know that soggy bread and I don’t mix. Do you find that with this recipe the bread gets soggy at the bottom when reheating?Thanks!

    PS – I made your 30 min soft pretzels the other night. SO easy and delicious served with the kicked up cheese sauce. Making some of those for the freezer too 🙂

    1. Nicole, I’m the same way– hate sogginess. But there is no soggy bread here when reheating. Since the bread is broken up into small chunks, it actually becomes part of the eggy mixture. So it’s more chewy than anything. I hope this makes sense! Congrats on your upcoming bundle of joy!

  19. Love your savory breakfast ideas! I made  probably for the 4th time) your very cheesy spinach mushroom quiche this week. I love, love it and ate it for breakfast a few days and then lunch. This looks delish as well !

  20. I am as excited to cook this as you are to share this amazing recipe with us. Looks so flavorful and tasty!

  21. Looks good & sounds good ! One question. In the actual recipe you say to put the broken up bread in then pour 1/2 of egg mix then meat & veggies then the rest of the eggs. In the bonus area below with the photos you say the meat & veggies go on top of bread then the egg mixture. Which way is right & does it matter. If I make this we will be eating it all week so I want it to come out perfect. Thank you for the recipe.

    1. Yep, it should be half egg mixture on the bread, veggies/meat, then the rest of the eggs. Thanks Jim! Enjoy.

  22. Whenever I see egg dishes, all I want to do is slather it all in ketchup. Mmm, Mmm. Condiment queen! This would probably be really good with farro as a vegetarian source of a crumbly sausage texture. It’s pretty close and it’s hearty! I’ll let you know if I try it! When do you leave for your tour, btw??

    1. Obviously ketchup is a must with this casserole. 😉

      I leave on October 7th! For practically 2 straight months!

  23. They look absolutely delicious and full of so much goodness! I wish I had one for breakfast right now! 🙂

  24. I love how customizable this recipe is. I usually like my eggs with mushrooms, spinach, and sausage.

  25. Yum, sounds pretty close to the strata I make pretty regularly, I like the extra veggies in yours! I also like to make it for dinner, it’s so easy and yummy!

  26. Jessie @ Chasing Belle says:

    Just pinned this for later! I plan on having neighbors over for a harvest brunch and this would be a great option! Thanks Sally and, oh, Happy Anniversary 🙂

    1. Thanks for the happy anniversary wishes! Hope the neighbors enjoy this.

  27. 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!

    1. Thanks for reporting back, Erin! You will love love love the french toast casserole too.

  28. Yummy!!! But, one thing, try to use lesser sausage. I heard that saysages contain MSG. If you don’t know what I mean, MSG is ised to flavour food and is bad for health

    1. Only bad for health if you use it too often.

      1. I’m just giving you some advice

    2. Why not make your own sausage? It’s so easy and no MSG needed. You just need ground pork and some spices. I used Fennel, Sage & Parsley and it’s delicious. I just made patties because I don’t have a machine to make links. Who cares? The patties are delicious and for this recipe, you need crumbled sausage anyway. Google “Homemade Breakfast Sausage recipe”. 

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

    1. Glad you love it! Thanks JoAnn.

  30. Peggy, Singapore says:

    Hi Sally, Gave this a go yesterday but used minced meat instead of sausages seasoned with oregano and basil. We loved I! There’s another serving waiting for us in the freezer. Thank you!

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