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.

clock clock icon cutlery cutlery icon flag flag icon folder folder icon instagram instagram icon pinterest pinterest icon facebook facebook icon print print icon squares squares icon
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. Hello! Can you make this two days ahead?

    1. Absolutely

  2. Do you know about how many calories are per serving? Thanks in advance!

    1. I don’t, sorry! Feel free to use a recipe calorie calculator (there are many online!).

  3. Do you drain the grease after you brown the sausage?? Thanks! 

    1. I don’t!

  4. I need to make it for 60 people.  I’m thinking about  baking it in a large aluminum pan.
    2 Large pans with each pan consisting of 2x your recipe portion.
    I’ll be serving it with a small cuban sandwich with some fruit.
    Do you think it will work baking in the aluminum pan, and do you think 4x will be enough?
    Love you hear your comment!


  5. Can this be frozen?

    1. Never mind.  If I had read to the end of the recipe I would have found my answer.  Yes, it can be frozen. 🙂

  6. Could you use diced or grated potatoes instead of bread

  7. Would you suggest ciabatta bread, and any nuts?

    1. You can use any bread you love!

  8. Does freezing change the texture of the eggs at all? Or does it taste the same? 

    1. No, it doesn’t:) bread is perfect even after being frozen.

  9. Hi there … a strange question, not about the recipe.

    You show in the pictures above a beautiful fork in a beautiful green color. May I ask where I can get that flatware set?

    I truly appreciate it.

    Thank you!!

    1. Hi Gail! The forks are form Anthropologie. I can’t find them anymore on the website at the moment!

  10. Sounds delicious. I am making for a crowd — can you double the recipe and cook in a steam table pan? How many recipes would you need for the large pan? How long would it need to cook? Thanks!!

    1. Just keep the pans to a max size of 9×13 that way your eggs and bread get done in the middle.

  11. Have you ever added hash browns to this recipe? How can I incorporate them-my family loves them in egg casseroles.

    1. I’ve had readers replace the bread with frozen hash browns. Yum!

  12. Can you make this withou the bread?

    1. Hi Kim, you can leave the bread out. The texture of the casserole will change– it will just be like baked egg rather than an egg casserole– but it will still have wonderful flavor.

  13. Can you use bacon instead of sausage? Is it best to let the bread get hard, so that when it’s soaking in egg overnight it won’t be soggy?

    1. You don’t want the bread to be super hard. I usually just leave it out on the counter for a day before I use it!

  14. I would like to make this 2 weeks before Christmas and freeze. Would this be okay being frozen for this long? Also, more importantly, do I have to cook it before freezing? Thank you so much!

    1. Hi Danielle! See the freezing instructions. They will help!

  15. I just got finished making my overnight breakfast egg casserole and got a phone call that the breakfast is postponed. Can I freeze it and bake it in a few days .?

  16. Have you ever left out the bread?

    1. Hi Dianne! On occasion, yes. The breakfast casserole prepared without bread is much more eggy tasting and has a flimsier texture. It tastes much heartier and substantial with the bread.

  17. Have you ever tried roasting the veggies on high heat in the oven? I find them to be much more solid, maybe even crispy (in a good way. I worry the Veggies with be soggy.

    1. Hi Allie! I haven’t tried it that way, but you certainly can. I just use the stove for the veggies. I don’t find the casserole tastes too soggy. The bread soaks up a lot of liquid.

  18. Sarah Hiatt says:

    Hi, what do you think about spicy sausage vs mild?

    1. Use any sausage you like. Spicy would add some great flavor!

  19. Gillian Laquis says:

    Hi does this recipe have to be put in th fridge for two hours? Have you ever baked it right after making?

    1. You can bake the casserole right away, but it tastes best when baked after the flavors have settled for a couple hours.

  20. Melanie Troxler says:

    I am very excited to try this recipe. Do you think it could be cooked in a Crock Pot?

    1. Hi Melanie! I can’t see why not 🙂 Let me know how it tastes!

  21. Don’t need all the small talk. Just give the recipe!

    1. Hi Janet! There is a Jump to Recipe button at the top of the blog post. You can click that next time. 🙂

    2. RUDE Janet!!

  22. Sounds very good with be my Thanksgiving breakfast this weekend.

  23. I noticed you said you’ve used broccoli before.. did you boil it first or just heat it up in the skillet? Excited to try it! Making it with broccoli, spinach, onion and kielbasa!

    1. Hi Liz! I actually boil it first. Helps cook it down a little before baking in the casserole.

  24. Kristina Smith says:

    looking for things to make for Christmas Brunch. I’ll be making the kids pancakes that look like Santa, whipped cream beard etc for breakfast, but I’m a savory girl. This looks AMAZING I want to eat it right this second. Can not wait to try.

  25. 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.

  26. If we substitute Frozen Hash Browns for the bread, how many cups or ounces of Frozen Hash Browns should we use?


    1. Hi Giselle! I’m unsure, just spread them in a thin layer in the bottom of the pan.

  27. 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!

  28. 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!

    1. Hi Alli! You can freeze the unbaked breakfast casserole (raw egg).

    2. This also freezes well before you bake it

  29. Hi-

    I am very interested in trying this recipe… can I do the casserole without the pieces of bread?

    I’m always on the go so this would be perfect for me to make in advance and just make it a breakfast sandwich with English Muffins the following morning.

    Thank you!
    This looks delish, I cannot wait to give it a try?

    1. Yes, it would be like a big baked omelet that way!

      1. Okay, awesome thank you! My thoughts were along that line but I wanted to confirm since it is your recipe, you would know better than me!

        Thank you so much!
        I am excited to give it a try!

      2. This casserole is SO tasty – I’ve made it many times before. I’m making it again this weekend and plan to leave the bread out (family in town is gluten free). Without the bread, do you need to adjust the cooking time at all? And if not using the bread, do I need to allow it to sit for 2-hours, or can I basically bake it after it’s assembled? Thank you!

      3. Hi Carrie! Bake time without the bread will be a little shorter. And no need to let it sit for awhile before baking. If I leave out the bread, I bake it right away!

      4. Could you also freeze it after it’s been cooked and cut up? Freeze the cooked portions and just defrost overnight and re heat in the microwave? Just would like it to be quicker to cook in the mornings? Thanks.

      5. Yes, you can try that, Laura.

    2. I am going to make this today for weekend guests. I was wondering about perhaps using potatoes/ hash browns on the bottom instead of the bread?

      1. I bet that would be delicious although I haven’t tried it!

      2. I love your idea of using potatoes. Do you use them raw? Or did you cook and/or saute them first before cooking in oven? Thank you!

  30. 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!

    2. I do similar just for me and make it in a muffin tin so it’s all individual portions! Loveeeeeee it and perfect size

1 2 3 4 5 6

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

With kitchen-tested quality recipes and step-by-step tutorials, my goal is to give you the confidence to bake and cook from scratch.

Sally's signature

Recipes You’ll Love



Join the community on the 1st of every month as we tackle a new challenge recipe.Review Sally's Baking Challenge FAQ page if you have any questions.

View More

A tradition since 2013, every December we countdown to Christmas with 10 new cookie recipes in a row!

View More

The first week of every November is all about Thanksgiving Pies.

View More

My Cookbooks

Sally's Cookbooks

About Sally

Welcome to my Kitchen!

I’m Sally, a cookbook author, photographer, and blogger. My goal is to give you the confidence and knowledge to cook and bake from scratch while providing quality recipes and plenty of pictures. Grab a cookie, take a seat, and have fun exploring! more about Sally