Breakfast Casserole: Overnight Sourdough Sausage Bake

The Ultimate Overnight Sausage, Cheddar, and Sourdough Breakfast Bake

That smell. Oh my god, that smell when the oven door opens? It’s rich, it’s savory, and it promises pure, unadulterated comfort. If you want to nail the holiday morning vibe or just feed a hungry crowd without breaking a sweat, you need this recipe for the ultimate breakfast casserole in your life.

It puffs up beautifully, turning deep golden brown, and the edges get that amazing crispy cheese crust.

Let's be real: mornings are chaos. Finding a recipe that handles 90% of the work the night before is the ultimate kitchen hack, especially if you have guests. This make-ahead breakfast casserole is cheap, uses pantry staples, and guarantees you look like a domestic genius when you finally pull it out of the oven.

It’s the perfect lazy weekend indulgence.

I’ve made every mistake with these bakes soggy bottoms, dry eggs, flavorless fillings. But this exact combination of sharp cheddar, savory sausage, and crusty sourdough delivers texture and deep flavor every single time.

Stop relying on questionable boxed mixes; let’s make the best sausage breakfast casserole you’ve ever tasted.

Why This make-ahead Egg Bake Recipe Stands Above the Rest

We aren't just dumping bread and eggs into a dish here. We are building flavor layers and maximizing texture contrast. If you follow my steps, particularly the overnight soak, your result will be moist, structured, and incredibly satisfying.

This is the difference between a sad, wet egg mush and a spectacular, structured breakfast casserole .

The Magic of Overnight Soaking for Deep Flavor

The overnight chill is non-negotiable, honestly. This process allows the sourdough bread cubes to slowly and completely absorb the egg custard mixture. If you skip this, the exterior bread gets soggy while the interior stays dry and crumbly during the bake.

The rest time means the whole overnight breakfast casserole cooks evenly, resulting in a creamy texture that sets perfectly.

Why Sourdough Provides the Superior Structural Base

I know people use basic white bread or even hash browns, but trust me on the sourdough. Sourdough has a much sturdier crumb and crust. It resists dissolving into the custard, which prevents that dreaded soggy bottom.

It keeps its shape, providing delightful pockets of airy texture in the finished breakfast casserole .

A Crowd Pleasing Holiday Morning Solution

Cooking for a crowd on Christmas or Easter should be fun, not stressful. Since this requires zero prep on the day of serving (except turning on the oven!), it means you actually get to drink coffee and relax while the make-ahead breakfast casserole bakes itself.

It truly is a holiday morning savior.

Achieving the Perfect Creamy Crispy Texture Balance

The balance comes from the fat content. We use whole milk AND a splash of heavy cream in the custard base. The higher fat content ensures a tender, creamy internal texture rather than dry, rubbery eggs.

Plus, using two cups of freshly grated sharp Cheddar guarantees a salty, caramelized crust around the edges of this magnificent cheddar breakfast casserole .

The Science of Egg Custard Absorption

We add Dijon mustard to the custard not because we want a mustardy flavor, but because the acid helps to stabilize the eggs and cut through the richness of the dairy. It's a secret weapon for achieving truly tender eggs in any savory bake.

This makes our egg custard base unbeatable for this particular breakfast casserole .

Flavor Depth: Building Savory Layers with Sausage and Cheese

We aren't just throwing raw ingredients together. We sauté the onions and peppers first to deepen their sweetness, then fully brown the sausage. This building of savory, caramelized flavors before assembly is what makes this the best sausage breakfast casserole recipe out there.

Essential Ingredients for Your Sausage and Cheddar Breakfast Casserole

You really only need seven main components for this masterpiece. Quality counts, especially for the cheese and the bread. This isn't the time to skimp!

Preparing the Components: Specific Prep Notes and Substitutions

Choosing the Right Sausage: Ground vs. Links

I always go for bulk ground breakfast sausage. It crumbles easily and distributes perfectly throughout the breakfast casserole . If you only have links, slice them thinly after they are cooked. Make sure you drain the cooked sausage completely before adding it to the bake.

Excess grease equals separated, oily eggs yuck.

The Best Cheeses for Melt and Flavor (Focusing on Sharp Cheddar)

You absolutely must grate your own cheese for this breakfast casserole . Pre-shredded cheese is coated in cellulose (an anti caking agent). That coating means it doesn't melt smoothly and you lose that luxurious ooze.

Sharp Cheddar offers the best salty bite that balances the richness of the sausage.

Chef’s Note: If you want a richer, nuttier flavor profile in your breakfast casserole, try swapping half the Cheddar for grated Gruyère or even Provolone.

Sourdough Bread Prep: Day-Old vs. Fresh

The bread should be slightly stale, or at least a day old. If your bread is super fresh and soft, cut it into cubes and leave it uncovered on the counter for a couple of hours. This little bit of drying time is key to ensuring the bread cubes maintain structure after the overnight soak in this sausage breakfast casserole .

Dairy Swap Guide: Using Milk, Half and Half, or Cream

This recipe calls for a mix of whole milk and heavy cream for maximum richness. If you need to lighten it up, you can use all whole milk. If you happen to have half and half on hand, use that in place of the milk and cream combination, but recognize that the final breakfast casserole will be slightly less decadent.

step-by-step Method: Assembling the Overnight Breakfast Bake

This is a two-day process, remember? Day one is assembly and soaking. Day two is the glorious bake!

Phase 1: Browning the Sausage and Aromatics

1. Prep the Pan: Grease a standard 9x13 inch casserole dish. This is a critical step for easy serving later.
2. Sauté: Melt 1 Tbsp of butter in a large skillet. Cook the diced onion and red bell pepper until they soften, about 5– 7 minutes. Remove and set aside.
3. Cook Sausage: Add the bulk breakfast sausage to the same skillet. Break it up and cook thoroughly until nicely browned. Drain off all the rendered fat. This prevents your entire breakfast casserole from becoming greasy.
4. Combine: Return the sautéed vegetables to the sausage. Stir in the sage and pepper.

Phase 2: Layering the Bread and Cheese Base

5. Bread Base: Distribute half of your 1 inch sourdough cubes evenly across the bottom of the prepared dish.
6. Filling Layer: Spoon the sausage and vegetable mixture evenly over the bread layer.
7. Cheese Sprinkle: Sprinkle 1 cup of the grated sharp Cheddar over the sausage filling.
8. Top Layer: Add the remaining bread cubes on top.

Phase 3: Whisking and Pouring the Egg Custard

9. Make the Custard: In a large bowl, whisk together the 12 large eggs, 2 cups whole milk, 1/2 cup heavy cream, the Dijon mustard, salt, garlic powder, and that tiny pinch of nutmeg. Whisk until it's light yellow and slightly foamy no streaks of unmixed egg white should remain.
10. Soak It Up: Pour the entire custard mixture evenly over the casserole dish, starting from the center and moving outwards. Gently press the top bread layer down to ensure maximum absorption.

Phase 4: The Overnight Chill and Baking Process

11. The Chill: Cover the dish tightly with plastic wrap. Place the overnight breakfast casserole in the fridge for at least 4 hours, but preferably 8– 12 hours. This soaking time is essential for the structure.
12. Preheat and Temper: Preheat your oven to 375°F (190°C). Take the casserole out of the fridge about 30 minutes before baking. Baking it straight from the fridge extends the cooking time unnecessarily and can lead to a raw center.
13. Bake: Cover the dish loosely with foil and bake for 35 minutes. This steaming prevents the top from drying out.
14. Finish: Remove the foil. Sprinkle the remaining 1 cup of Cheddar over the top. Bake for an additional 15– 20 minutes, or until the cheddar breakfast casserole is deeply golden brown and the center is set.

Mastering the Bake: Chef's Pro Tips and Troubleshooting Common Mistakes

I have made almost every casserole mistake possible, from rubbery eggs to sad, weeping corners. Here are the secrets I learned the hard way to ensure your sausage breakfast casserole is perfect.

Preventing a Soggy Bottom: Key to a Successful Bake

The main culprit of sogginess is fat or fresh bread. First, make sure you drain that sausage grease thoroughly. Second, use stale or day-old sourdough; it stands up beautifully to the liquid.

If you still worry about the bottom, try sprinkling a thin layer of dry breadcrumbs (like Panko) on the bottom of the greased pan before adding the cubed bread. This acts as a moisture buffer for the easy breakfast casserole .

Checking for Doneness: The Center Temperature Test

The knife test works, but the thermometer test is better. The eggs should be fully set, reaching an internal temperature of 160°F (71°C) in the very center. If the temperature is lower, or if the knife inserted comes out wet, put it back in!

Nobody wants raw egg in their make-ahead breakfast casserole .

Achieving a Golden Brown Top Crust

The final 15– 20 minutes of uncovered baking is when the magic happens. We add the rest of the cheese then so it melts beautifully and gets crispy edges without burning. If the top is browning too quickly, simply put the foil back on loosely for the last few minutes.

This ensures the custard sets before the crust burns.

Mistake I Once Made: Too Much Salt

My rookie mistake was forgetting how salty bulk breakfast sausage and sharp cheddar already are. Be conservative with the salt in the custard mix initially. You can always add a pinch of flaky salt on top after it bakes, but you can’t take salt out!

This is especially true for any hearty breakfast casserole involving cured meat.

Storing, Freezing, and Reheating Instructions

You made a giant, beautiful breakfast casserole . Now what? Planning leftovers is just as important as the initial cooking process!

Freezing Unbaked vs. Baked Casserole Sections

This is excellent for freezing! You can freeze the entire thing unbaked. Follow all assembly steps, cover tightly (using both plastic wrap and foil), and freeze for up to 3 months. When ready to bake, transfer the frozen breakfast casserole directly to the oven.

You will need to add about 30– 45 minutes to the initial covered bake time.

If you have leftovers of the baked breakfast casserole , slice it into individual portions first. Wrap each portion tightly in foil, then place them in a freezer bag. This makes reheating quick and easy perfect for grab and go breakfasts, perhaps alongside a high protein Bariatric Seed Recipe: 10 Minute High Protein Breakfast Prep .

Reheating Leftovers Without Drying Out

For individual slices, the microwave works fine in a pinch. But for the best texture, reheat slices in a toaster oven or standard oven at 300°F (150°C) until warmed through, about 15– 20 minutes.

If reheating a large section of the cheddar breakfast casserole , cover it loosely with foil to retain moisture.

How Long Does This Breakfast Bake Last?

If stored correctly in an airtight container, this spectacular sausage breakfast casserole lasts safely in the refrigerator for 3 to 4 days. It makes brilliant meal prep for busy weekdays!

Perfect Pairings and Serving Suggestions

Since this best breakfast casserole recipe is savory and rich, you need elements of acidity, freshness, or sweetness to balance the plate.

• Acidity: Serve with a bright, crisp green salad tossed in a simple lemon vinaigrette. A small dish of salsa or a dollop of hot sauce works wonders, too.
• Sweetness: A simple fruit salad featuring seasonal berries, segmented oranges, or some caramelized pineapple rings adds welcome brightness.
• Another Breakfast Star: If you’re really throwing a brunch bash, pair a smaller slice of this hearty bake with something lighter and fluffier, like my classic Hootenanny: Easy Baked Pancake Recipe for a Puffy Breakfast .
• Drink Pairing: Strong coffee, obviously. For celebrations, a refreshing pitcher of Mimosas or sparkling cider is always a winner.

This overnight breakfast casserole truly is the ultimate champion of make-ahead meals. It's cheesy, savory, and tastes like you spent hours slaving away, even though the fridge did most of the heavy lifting.

Go make it this weekend you won’t regret having a batch of this deliciousness ready to go!