Sourdough Breakfast Casserole

This healthy Sourdough Breakfast Casserole Recipe is packed full of vegetables, healthy fats, and protein. Made in a 9×13” pan it is great for a crowd or is an easy way to meal plan breakfasts for the week. Simply put it together the night before, bake in the morning, and you’re ready to feed the whole family! It is the perfect way to use up extra sourdough bread, or even better stale sourdough bread, and is easily customized based on what you have on hand. 

Breakfast casseroles are such an easy way to get a hearty breakfast on the table! All you need is a slice of the casserole and you have all the components of a nutritious, filling breakfast! My family loves to top this casserole with salsa or guacamole, but it also is just as tasty left plain. More protein packed sourdough breakfast ideas include Protein Sourdough Pancakes, or Protein Sourdough Waffles. Or, go indulgent and make Sourdough Bread French Toast Casserole or Sourdough Cinnamon Rolls.

Why you’ll love this recipe

• Customizable- make this with or without meat, add in your favorite veggies or whatever you have on hand, and top with your favorite toppings like salsa, hot sauce, or guacamole
• Healthy and nutritious breakfast- this keeps you full for longer and is well-balanced with carbs, healthy fats, and protein. It’s a great way to get in a serving of veggies for breakfast.
• Feeds a crowd- it’s a great option when feeding a crowd or for a smaller family make it once and you have breakfast taken care of for the week! 
• Uses up stale sourdough bread- it’s always a bummer when sourdough bread goes stale but not to worry, with this recipe you give new life to hard sourdough bread. 

Why use stale sourdough bread?

This recipe is a great use for sourdough bread going stale on your counter! When bread is stale, it starts to go hard, and while this isn’t ideal for something such as fresh sandwiches, using stale bread in this recipe absorbs more of the moisture from the eggs. However, using a fresh loaf of crusty, artisan sourdough bread works well too. If you use soft sourdough sandwich bread, cut the sourdough bread into cubes and add it to a sheet pan. Pop it into the oven at 350 degrees for a few minutes until the bread feels slightly hard.

Do I have to make this recipe the night before? 

Assembling the casserole the night before you bake it not only saves you time in the morning but also allows the bread to soak up all the flavor. Although you also could assemble and bake right away, I think you’ll love how easy it is to prep breakfast ahead of time! This is a great recipe to use for a Sunday morning brunch, breakfast for dinner, or to feed a crowd. 

Sourdough Breakfast Casserole Ingredients

• Sourdough bread – use artisan sourdough bread and cut it into cubes. 
• Eggs- If you prefer a lower fat option you can swap out for 1 cup of egg whites.
• Milk- Any type will work or you can even use a dairy-free alternative if needed. 
• Shredded cheese- I like cheddar but feel free to use any type of shredded cheese you have on hand. 
• Adobo Seasoning – this is optional but adds a great flavor
• Garlic Salt
• Everything but the bagel seasoning blend- this is optional but adds a great flavor
• Yellow onion- You can finely chop or dice the onion depending on what you prefer. 
• Veggies of choice- Use any veggie you have on hand or any combo you enjoy. For this recipe, I used red bell peppers, mushrooms, and spinach but tomatoes, broccoli, and/or asparagus would also be great. 

Optional add-ins

My favorite thing about this recipe is how versatile it is! You can make this a meatless breakfast and use only veggies, or you can add in any meat you’d like. Feel free to add in bacon crumbles, a package of cubed ham, or breakfast sausage. Just be sure to precook the meat before adding it to the casserole to ensure it is cooked through. 

How to Make the Sourdough Breakfast Casserole 

To assemble the night before, cut your sourdough bread into cubes. You will need 6 cups of bread cubes, which is about half of a large loaf. If your bread is soft you can cut it into cubes add it to a sheet pan and then pop it into a 350-degree oven for a few minutes until the bread feels slightly hard. If you want to make fresh sourdough bread, use my simple overnight sourdough recipe, or same day sourdough bread recipe.

Next, dice up your onion and your choice of extra veggies. You will want about 2 cups of extra veggies. For this recipe, I used 1 cup of red bell pepper, ½ cup of mushrooms, and 1 cup of spinach. 

If you are choosing to add meat to your casserole, cook raw meat until cooked through. Or you can use leftover meat or one that is pre-cooked, such as ham. 

In a large bowl, add the eggs, milk and seasoning. Whisk to combine together. Then add in half the cheese, veggies, optional add-ins, and bread cubes. Stir to combine everything. 

Spray a 9×13 pan with cooking oil and place the mixture in the dish. Add the second half of the cheese on top. 

If you assembled the casserole the night before, cover the unbaked casserole and sit in the fridge overnight. You can leave the casserole unbaked in the fridge for up to 24 hours. This gives the bread time to soak up the liquid and flavor and is worth the wait!

The next morning, preheat the oven to 350 degrees Fahrenheit. Add the casserole to the hot oven and bake for 50 minutes or until the egg mixture is cooked through.

To serve, remove from oven and let it sit for 5 minutes. Then slice it into 8 slices and serve. The casserole is filling and great served on its own, or you can pair it with a side of fresh fruit. 

Optional toppings

Get creative and add some toppings to the casserole! My favorite is guacamole and salsa, or hot sauce would be great as well! You could also top it with fresh herbs such as chives, parsley, or cilantro. 

How to store

Store the sourdough breakfast casserole in an airtight container in the fridge for up to 3-4 days. This is a great recipe to use for meal prep and have breakfast ready throughout the week! You can reheat in the microwave or pop into the oven at 350 degrees until it has heated through.