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A good breakfast casserole is a lifesaver—not just for special occasions like Christmas morning but for any day you want a comforting, make-ahead meal.

That’s why I love this Sourdough Breakfast Casserole it’s simple, satisfying, and easy to make ahead!

Whether you’re hosting brunch, prepping for busy mornings, or adding something special to a holiday table, this casserole is a surefire winner.

We originally fell in love with this recipe as part of our Christmas morning tradition, but honestly, it’s perfect all year round.

If you’re in the mood for something sweet, be sure to check out my Sourdough Blueberry Stuffed French Toast Casserole. It’s a completely different take on breakfast casseroles, offering rich, fruity flavors that are just as crowd-pleasing.

Why Sourdough?

Sourdough bread is so much more than delicious—it’s a nutritional powerhouse. Thanks to the natural fermentation process, sourdough is easier to digest and often more nutrient-rich than other breads.

The fermentation breaks down gluten and phytic acid, making the nutrients in the bread more bioavailable.

Plus, sourdough has a lower glycemic index, helping to keep blood sugar levels steady.

For this recipe, I recommend using homemade sourdough or The Essential Baking Company’s Sourdough.

I love their bread because it’s organic, true sourdough with no added yeast, and packed in vacuum-sealed packaging that extends its shelf life without sacrificing quality.

It’s also easy to find—you can order it online, but the best deal is at Costco (here in Washington, we pay about $13 for a 3-pack box).

Not only is it better for your body, but its hearty texture ensures this casserole comes out perfectly every time.

Ingredients You’ll Need

This recipe is endlessly adaptable, but here’s the base for the classic version:

6 cups sourdough bread, cubed: A hearty bread works best for structure.
1 pound of your favorite protein: Think cooked sausage, diced ham, or cooked bacon.
1 ½ cups shredded cheese: Cheddar, Monterey Jack, or Gruyère add a creamy, savory element.
8 large eggs
2 cups milk
1 teaspoon salt
½ teaspoon black pepper
Gravy:
- 1 cup milk
- 1 tablespoon all-purpose flour
- 1 tablespoon butter or fat of choice
- Salt and pepper to taste

How to Make It

1. Prep Your Baking Dish

Grease a 9x13 baking dish with butter or non-stick spray. Layer the sourdough cubes evenly in the dish, followed by your chosen mix-ins and cheese.

2. Make the Custard

In a large mixing bowl, whisk together the eggs, milk, salt, pepper, and any herbs you'd like to add. Ensure everything is well combined for an even bake.

3. Pour and Soak

Pour the custard mixture evenly over the bread and toppings, pressing gently to help the bread absorb the liquid.

4. Make the Gravy

In a small saucepan, melt the butter over medium heat. Whisk in the flour and cook for 1-2 minutes until lightly golden. Slowly pour in the milk, whisking constantly to prevent lumps. Season with salt and pepper to taste, and continue stirring until the mixture thickens into a smooth gravy.

5. Add the Gravy

Once the bread has soaked in the custard, pour the prepared gravy evenly over the top of the casserole. This extra layer adds a rich, creamy finish that elevates the dish.

6. Rest (Optional)

For the best texture and flavor, cover the dish and refrigerate it overnight. If you're short on time, let it sit for at least 30 minutes before baking.

7. Bake

Preheat your oven to 350°F (175°C). Bake the casserole uncovered for 40-50 minutes, or until the top is golden and the center is set.

8. Serve

Let the casserole cool slightly before slicing and serving. Garnish with fresh herbs or a sprinkle of cheese for extra flair.

Why We Love It

Make-Ahead Convenience: Assemble the night before, then bake in the morning for a stress-free meal.
Customizable: Swap in your favorite cheeses, meats, or veggies to suit your family’s preferences.
Perfect Christmas Morning Casserole: This casserole has become a Christmas morning tradition in our home. It’s warm, hearty, and filling—just the thing to enjoy while unwrapping gifts and spending time with loved ones.

Storage and Reheating

This casserole is just as delicious the next day!

Refrigerate: Store leftovers in an airtight container for up to 3 days.
Reheat: Bake the whole dish at 300°F for 15-20 minutes or warm individual portions in the microwave
Freeze: Wrap tightly and freeze for up to 2 months. Thaw overnight in the fridge before reheating.

While this casserole holds a special place in our hearts as a Christmas morning favorite, it’s versatile enough for any day.

Whether you’re hosting brunch, prepping for a busy workweek, or just indulging in the comforting flavors of sourdough, this breakfast casserole is a recipe you’ll return to again and again. Hugs!