Sourdough Breakfast Casserole
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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. I love serving for it special occasion breakfasts too because it's so easy to prep ahead - hello Christmas morning!
This sourdough breakfast casserole can also be referred to as breakfast strata or savory bread pudding, depending on where you come from.
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 and protein. 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.
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.
Ingredients
- Sourdough Bread - I've used a loaf of my simple sourdough bread, but you can use any sourdough bread you like!
- Olive Oil
- Ground Pork Sausage (casings removed) - If you can't get ground pork sausage, then turkey sausage would be the next best alternative. 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.
- Rosemary - I've used dried rosemary here, but of course you can use fresh if you prefer, in fact you can use any fresh herbs you like. I often use fresh thyme as I've always go this in my garden year round. You could also use dried oregano or Italian Seasoning.
- Yellow Onion
- Garlic - fresh, minced garlic cloves are best, but you can use garlic from a jar or garlic granules too if you like.
- Bell Peppers - I use whatever color I can get at the grocery store. It looks more festive when you use red, green and yellow but for these photos I've just used red and yellow.
- Eggs (large, around 60 to 70g in size)
- Sourdough Starter - you can use active starter or sourdough discard, whatever you have on hand is fine.
- Salt and Black Pepper
- Milk - whole milk is best, but reduced fat works too.
- Cheddar Cheese - shredded sharp cheddar cheese is best, but you could also just use your favorite cheese. I love adding some gruyere if I have it on hand.
How To Make Sourdough Breakfast Casserole
This sourdough breakfast casserole is everything you want in an easy, make-ahead morning bake. You can assemble it in a classic 9x13" dish or go rustic with a large 12" cast iron skillet, either way, the sourdough bread cubes soak up all the savory goodness while still giving you those irresistible crunchy edges.
Start by layering your torn or cubed sourdough in the prepared pan, then cook up a simple sausage-and-veggie mix packed with rosemary, garlic, and colorful peppers.
Once that golden, fragrant mixture is ready, it gets scattered over the bread to create the base of the casserole.
The real magic happens when you whisk together the eggs, milk, sourdough starter, and cheese, then pour it over everything and let the whole dish rest.
An overnight soak is ideal, giving the sourdough time to absorb all the custardy flavor so the casserole bakes up tender, hearty, and full of savory pockets. When you’re ready to serve, it bakes to a beautifully golden top and slices like a dream. Finish with green onions, fresh chives or herbs, and if you love sweet-meets-savory, a drizzle of maple syrup is surprisingly perfect.
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).
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.
Frequently Asked Questions
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.
No, the sourdough bread won’t dissolve. It may soften as it soaks overnight, but once baked, the egg mixture sets into a rich, custardy base while the top turns beautifully golden and crisp—giving you the perfect balance of soft and crunchy in every bite.
To reheat this breakfast casserole, place it in a preheated 180°C (350°F) oven, covered with foil, for about 20–30 minutes or until warmed through. Covering it prevents the top from over-browning while the centre heats evenly. For individual portions, you can microwave them in 30-second bursts until hot, though the oven will always give you the best texture.
Sourdough Breakfast Casserole
Equipment
- Cast Iron Skillet or Baking Dish (this recipe works in a 12" cast iron skillet or round baking dish or 9" x 13" rectangle baking dish)
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 teaspoon Rosemary (or Oregano or Italian Seasoning)
- 100 g Yellow Onion (one small onion, diced)
- 2 cloves Garlic (minced or can use garlic granules)
- 300 g Bell Peppers (yellow, green, red - diced)
- 12 Eggs (large, around 60 to 70g in size)
- 100 g Sourdough Starter (or sourdough starter discard)
- 1 teaspoon Salt
- 1 teaspoon Pepper
- 160 g Milk (whole milk)
- 120 g Cheddar Cheese (shredded)
Instructions
- Before you start, grease a baking dish or skillet with cooking spray, butter or oil. Set this 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.
- Heat a frying pan over high heat. Add the olive oil and fry the ground pork sausage and rosemary (or whatever herbs you choose to use) 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.
- 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 eggs, sourdough starter, salt, 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.
- Now, cover the dish in aluminum foil and place into the fridge for up to 24 hours. This allows the crusty sourdough bread to absorb all of the egg mixture.
- When you're ready to bake the sourdough breakfast casserole, preheat the oven to 200ºC (400ºF) and allow the breakfast casserole to sit out of the fridge for around 30 to 40 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.
Notes
Nutrition
