Name: Sourdough Breakfast Casserole
Prep time: 25 min
Cook time: 45 min
Total time: 130 min
Ingredients: 500 g Sourdough Bread ((approx. half a loaf, cubed - see notes)); 20 g Olive Oil; 500 g Ground Pork Sausage ((casings removed - see notes)); 1 tsp Rosemary ((or Italian Seasoning)); 100 g Yellow Onion ((one small onion, diced)); 2 cloves Garlic ((minced)); 300 g Bell Peppers ((yellow, green, red - diced)); 12 Eggs; 100 g Sourdough Starter ((or sourdough starter discard)); 1 tsp Salt; 1 tsp Pepper; 160 g Milk ((whole milk or half n half)); 120 g Cheddar Cheese ((shredded))

You are going to LOVE this sourdough breakfast casserole, made with homemade sourdough bread, sourdough starter, sausage, vegetables and lots of fresh eggs! This easy breakfast casserole recipe is the perfect make ahead breakfast for busy weekdays or even a nice, leisurely weekend brunch with no prep.

This sourdough breakfast casserole can also be referred to as breakfast strata or savory bread pudding, depending on where you come from.

If you love sourdough breakfast recipes, then make sure you check out this sourdough hash brown casserole, sourdough cinnamon rolls or even this sweet sourdough bread pudding.

A baking dish containing baked sourdough breakfast casserole. There is a red, white and blue dish towel underneath the baking dish.

Why You'll Love This Recipe!

Wholesome Breakfast - this easy to prepare savory breakfast casserole uses wholesome ingredients to create a breakfast casserole full of vegetables, protein and carbohydrate. A nutritious sourdough breakfast for the whole family!

Use Up Leftover Sourdough Bread - If you've got leftover sourdough bread to use up, then this recipe will help you use it without waste. You'll also use up 100g of sourdough starter or sourdough discard for the egg mixture too.

Use Lots of Eggs - if you have backyard chickens and you're overrun by fresh eggs, this sourdough breakfast casserole is the perfect way to use them up. Using a whole dozen eggs, this sourdough recipe is perfect for using up lots of eggs.

How To Make Sourdough Breakfast Casserole

I've made this easy sourdough breakfast casserole recipe in a 9" x 13" casserole dish, however you can easily make it in a cast iron skillet if you prefer. I recommend a large skillet to ensure you get plenty of crunchy top!

Flat lay of ingredients necessary to make sourdough breakfast casserole.

Before you start, grease a 9" x 13" baking dish with cooking spray, butter or oil. Set this greased baking dish aside.

Cube up your sourdough bread and arrange in the base of the baking dish. Allow to sit while you organise the rest of the ingredients.

Sourdough bread that has been cubed up ready to make sourdough breakfast casserole.

Heat a frying pan over high heat. Add the olive oil and fry the ground pork sausage and rosemary together. Use a wooden spoon to break up the sausage as it cooks. Make sure it's getting nice and brown as you break it up.

Once the sausage has browned, add the onion, minced garlic and bell peppers to the pan and fry off until the onion and pepper start to soften a little. I've used a red pepper, along with yellow and green, but use whatever peppers you can get.

Once the sausage and vegetable mixture is cooked through, carefully tip it over the sourdough bread cubes and spread it out evenly. Set this aside while you make the egg mixture.

In a batter jug, add 12 large eggs, sourdough starter, salt, black pepper, milk and shredded cheddar cheese (I've add a little extra Italian seasoning here too). Whisk vigorously until the ingredients are well combined.

Tip the egg mixture over the sourdough bread and vegetable mixture in the baking dish.

A casserole dish containing sourdough breakfast casserole that is ready to be baked in the oven.

Now, cover the dish in aluminum foil and place into the fridge for up to 24 hours (minimum 30 minutes). This is what makes this sourdough breakfast casserole the perfect make ahead dish!

When you're ready to bake the sourdough breakfast casserole, preheat the oven to 200C (400F) and allow the breakfast casserole to sit out of the fridge for around 30 minutes. Take the aluminum foil off the baking dish and place into the oven to bake until golden brown for around 45 minutes.

Once baked, remove from the oven and allow it to sit for around 30 minutes before serving. Top with green onions for a fresh garnish (totally optional). I love drizzling it with a little maple syrup before eating (trust me, it works).

What Type of Sourdough Bread to Use for Breakfast Casserole?

The great thing about this easy overnight sourdough breakfast casserole is that you can really use any sourdough bread you like! I've used half of my basic sourdough bread loaf. But you can really use any type of bread you like.

It's great for using up the last bit of sourdough sandwich bread, sourdough discard sandwich bread or even this sourdough jalapeno cheddar loaf (which gives this delicious breakfast casserole a spicy kick).

My kids love it when I use leftover sourdough cheese bread to make it (which is rarely because they usually eat all the cheese bread before I get a chance).

I find it's best to use stale sourdough bread that's a few days old as it absorbs all the lovely egg mixture better. Of course if you want to use fresh you can!

Another way to "stale" your sourdough bread is to cut it into cubes and lightly toast in the oven before proceeding with the recipe.

Which Sausages to Use?

I recommend using ground pork sausage for this recipe. Just remove the casings and fry the seasoned ground pork sausage in a pan. If you can't get ground pork sausage, then turkey sausage would be the next best alternative.

Beef sausage is also ok, just make sure that the sausage meat isn't too grisley. I think one of the most important things is that the sausage mixture you use has been seasoned. If you are using just plain ground pork meat, you'll need to add some extra herbs and salt to increase the flavor of the casserole.

For the casserole you can see in the photos, I've used pork breakfast sausage (also known as Cumberland sausage). This is seasoned with sage and I love the way this works in the casserole as a whole.

How To Make Sourdough Breakfast Casserole Ahead of Time

This sourdough breakfast casserole is just perfect to make ahead. You can easily turn it into overnight breakfast casserole. This makes a wonderful Christmas morning breakfast, prepped on Christmas eve. All you need to do it prepare the casserole following the instructions in the recipe card. Once it's assembled, cover with aluminum foil and place into the fridge for up to 24 hours.

Take the casserole out of the fridge and let it sit out at room temperature for 30 minutes before you bake it in the oven - always bake with the aluminum foil removed so that the top can get all golden and crunchy. Voila, perfect holiday breakfast! I love serving this casserole with some fresh fruit on special holiday mornings. It makes our mornings feel extra luxurious!

What Else Can You Add To Sourdough Breakfast Casserole?

While I love this sourdough breakfast casserole just as it is, there are lots of things you can add to it to both increase the nutrition and change the flavors a little bit. Here are some ideas for you:

Spinach & Mushroom - you can add a few handfuls of baby spinach and chopped mushrooms to the vegetable mixture (just add when you add the peppers).
Bacon - I love adding some diced bacon and an extra sprinkle of sharp cheddar cheese to the top of the casserole before baking this sourdough breakfast strata. It makes it extra special!
Jalapeno Cheddar - for something extra spicy, make this sourdough breakfast casserole using some leftover sourdough jalapeño cheddar loaf! It's sooooo good!

How To Store + Freeze

Once baked, this sourdough breakfast casserole can be stored in the fridge for up to 3 days. You can reheat the whole thing in the oven, or just reheat portions in the microwave.

You can freeze the baked sourdough breakfast casserole either as a whole, or sliced into portions. It can be frozen for up to 2 months. Thaw at room temperature and enjoy either hot or cold.