6-Ingredient Christmas Breakfast Casserole for Stress-Free Mornings

Name: 6-Ingredient Christmas Breakfast Casserole for Stress-Free Mornings
Prep time: 15 min
Cook time: 50 min
Total time: 1 h 5 min
Cuisine: American
Ingredients: 6 large eggs; 2 cups milk; 1 teaspoon salt; 1/2 teaspoon black pepper; 1 teaspoon dried mustard; 6 slices bread, cubed; 1 pound cooked sausage, crumbled; 1 cup shredded cheddar cheese; 1/2 cup diced bell peppers; 1/2 cup diced onions

Author: Carry

Published: November 1, 2025

Christmas breakfast casserole (make‑ahead)

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Picture this: Christmas morning, the kids are bouncing with excitement, presents are being unwrapped, and the scent of cinnamon rolls should be filling the air… but who has time to cook? That’s where this make-ahead Christmas breakfast casserole swoops in to save the day. I learned the hard way—after one too many frazzled mornings—that prep is everything. Now, I assemble this beauty the night before, pop it in the fridge, and bake it while we open gifts. No stress, no mess, just warm, cheesy, sausage-studded perfection ready when we are. It’s like a holiday miracle in a 9×13 dish.

Why You’ll Love This Christmas Breakfast Casserole (Make‑Ahead)

Listen, I’m not exaggerating when I say this casserole is a game-changer for Christmas morning. Here’s why it’s become my non-negotiable holiday tradition:

Time-saving magic: Assemble it the night before while sipping eggnog—no 6 AM kitchen chaos. Just slide it into the oven come morning.
Feeds a crowd effortlessly: That 9×13 pan stretches to feed hungry relatives, unexpected guests, and even seconds for Uncle Joe (you know how he is).
Totally customizable: Swap sausage for bacon, add mushrooms, or go veggie-heavy—it’s forgiving like that. My kids insist on extra cheese (shocking, I know).
Leftovers reheat like a dream: Because let’s be real, you’ll want this cheesy goodness for Boxing Day brunch too.

Trust me, once you try this make-ahead Christmas breakfast casserole, you’ll wonder how you ever survived holiday mornings without it.

Ingredients for Christmas Breakfast Casserole (Make‑Ahead)

Here’s everything you’ll need for this holiday lifesaver—measurements matter here, so don’t eyeball it! I’ve learned the hard way that precision makes all the difference with this recipe. Pro tip: Gather everything on the counter before you start. Holiday cooking should be joyful, not a scavenger hunt through the fridge.

6 large eggs (trust me, jumbo eggs make it too wet)
2 cups milk (whole or 2%—skim will leave it sad and dry)
1 teaspoon salt (I use kosher for even distribution)
½ teaspoon black pepper (freshly cracked if you’re feeling fancy)
1 teaspoon dried mustard (the secret weapon for depth)
6 slices bread, cubed (stale is actually better—no waste!)
1 pound cooked sausage, crumbled (I prefer mild, but spicy works)
1 cup shredded cheddar cheese, packed (sharp cheddar = flavor bomb)
½ cup diced bell peppers (any color—I do half red, half green for Christmas)
½ cup diced onions (sweet yellow or red onions work great)

See that dried mustard? Don’t skip it! That little teaspoon is what gives this casserole its “what IS that delicious flavor?” factor. And about the bread—day-old French bread or even hearty sandwich bread works wonders here. Fresh bread turns to mush, and we want those cubes to soak up all that eggy goodness without disappearing.

How to Make Christmas Breakfast Casserole (Make‑Ahead)

Okay, let’s get to the good stuff! This is where the magic happens. Follow these steps, and you’ll have the most glorious, puffy, golden-topped casserole ready when the stockings are empty and the coffee is poured. Don’t worry—it’s foolproof. (And if I can do it with a toddler clinging to my leg, you’ve got this!)

Step 1: Prepare the Egg Mixture

Grab your biggest bowl—you’ll need the space! Crack those 6 eggs in there and whisk them like you mean it. We’re talking smooth, pale yellow, no streaks. Now pour in the milk and keep whisking until it’s all best friends. Add the salt, pepper, and that sneaky-good dried mustard. (Pro tip: If you hate lumpy mustard, dissolve it in a splash of milk first.) Give it one last vigorous whisk—this is your casserole’s flavor foundation, so no slackers!

Step 2: Layer the Casserole

Time to build! Grease that 9×13 dish like you’re frosting a cake—get into the corners. Toss in your bread cubes first; they’re the cozy base. Next, sprinkle that glorious sausage evenly—no clumping! Follow with cheese (I may or may not sneak extra). Finally, scatter the peppers and onions like confetti. Now, here’s the key: Gently press all the layers down with clean hands. Not too hard—just enough so everything snuggles together before the egg bath.

Step 3: Chill Overnight

Pour the egg mixture slowly over everything—pretend you’re drizzling caramel on a sundae. Cover tight with foil (no peeking!) and let it sleep in the fridge overnight. This isn’t just about convenience—that long soak transforms the bread into custardy clouds and lets the flavors marry. I promise, it’s worth the wait!

Step 4: Bake to Perfection

Christmas morning! Preheat that oven to 350°F—no shortcuts here. Take the casserole out while the oven heats (about 20 minutes) to take the chill off. Bake uncovered for 45-50 minutes. You’ll know it’s done when the top is golden, the edges are bubbly, and the center doesn’t jiggle when you nudge the pan. If you’re unsure, slide a knife in—it should come out clean. Let it rest 5 minutes (torture, I know) so it sets up perfectly for slicing.

Christmas breakfast casserole (make‑ahead) - detail 1

Tips for the Best Christmas Breakfast Casserole (Make‑Ahead)

After making this casserole every Christmas for the past decade (and plenty of happy accidents along the way), I’ve nailed down the tricks that take it from good to “can I get this recipe?” status. Here are my hard-won secrets:

Broil for a golden finish: If your casserole needs more color after baking, pop it under the broiler for 1-2 minutes—just until the top gets that irresistible crispy crunch. (Watch it like a hawk though—it goes from perfect to burnt fast!)
Day-old bread is your friend: Fresh bread turns mushy, but slightly stale bread holds its structure while soaking up all that custardy goodness. No stale bread? Toast fresh cubes at 300°F for 10 minutes first.
Drain that sausage grease well: I learned this the messy way—too much fat makes the casserole weep oil. After browning, drain sausage on paper towels before adding.
Room temp ingredients blend better: Let eggs and milk sit out 20 minutes before mixing—cold ingredients can make the casserole bake unevenly.
The poke test never lies: If the center still jiggles, give it 5 more minutes. It should feel firm but springy, like a perfectly set cheesecake.

Follow these tips, and your make-ahead Christmas breakfast casserole will earn a permanent spot in your holiday rotation—just like it has in mine!

Ingredient Substitutions & Variations

One of the best things about this Christmas breakfast casserole is how adaptable it is! Over the years, I’ve tweaked it for every dietary need and whim—here are my favorite swaps that still deliver that holiday magic:

Meat lovers: Swap sausage for crumbled bacon, diced ham, or even chorizo (adds a spicy kick!). Just keep it to 1 pound total.
Vegetarian twist: Skip the meat entirely and double up on veggies—sautéed mushrooms and spinach work wonders. (Psst—add a pinch of smoked paprika for that “meaty” depth.)
Gluten-free: Use your favorite GF bread—the sturdier the better. I’ve had great results with sourdough-style GF loaves.
Cheese choices: Cheddar’s classic, but Gruyère or pepper jack make it extra special. Dairy-free? Violife’s cheddar-style shreds melt surprisingly well.
Veggie boost: Throw in a handful of thawed frozen spinach (squeezed dry!) or roasted red peppers for color. Just don’t exceed 1 cup extra veggies total—too much moisture throws off the balance.

The beauty? However you tweak it, this make-ahead casserole still delivers that cozy Christmas morning feeling.

Serving & Storing Christmas Breakfast Casserole (Make‑Ahead)

Here’s the best part—after all that waiting, you get to dig in! But hold your horses for just 5 minutes after baking. I know it’s tough with those cheesy smells wafting through the house, but letting it rest means cleaner slices that hold their shape. Leftovers? (As if!) Store them covered in the fridge for 3-4 days. When reheating, skip the microwave—toss slices in a 350°F oven for 10 minutes to bring back that glorious crispy top. Pro tip: Freeze individual portions before baking for instant holiday mornings all year!

Nutritional Information

Just a quick note before you dive in—these numbers are ballpark estimates based on the exact ingredients I use. Your mileage may vary depending on your sausage’s fat content, cheese brand, or whether you go wild with extra veggies (no judgment here!). One thing’s for sure: This Christmas breakfast casserole keeps you full through present-opening marathons.

FAQs About Christmas Breakfast Casserole (Make‑Ahead)

Got questions? I’ve got answers! After years of making this casserole (and fielding texts from family members mid-recipe), I’ve rounded up the most common queries. Here’s everything you need to know to nail your make-ahead Christmas breakfast casserole:

Can I freeze it? Absolutely! Assemble the casserole as directed, but skip the baking. Wrap it tightly in plastic wrap and foil, then freeze for up to 2 months. Thaw overnight in the fridge before baking—easy as pie (or casserole!).
Can I use fresh peppers? Yes, but sauté them first! Fresh peppers release water during baking, which can make the casserole soggy. A quick 2-3 minute sauté with the onions dries them out just enough.
How long does it keep? Leftovers (if you have any!) stay fresh in the fridge for 3-4 days. Just reheat slices in the oven at 350°F for 10 minutes—microwaving can make the bread mushy.
Can I make it gluten-free? Totally! Swap regular bread for a sturdy gluten-free loaf. I’ve found GF sourdough works best—it holds up to the egg mixture without turning to mush.
What if I don’t have dried mustard? No worries! Use 1 tablespoon of Dijon mustard instead—it adds the same tangy depth. Or skip it entirely, but trust me, it’s worth tracking down!

There you have it—your go-to guide for all things casserole. Now go forth and conquer Christmas morning with confidence!