The morning of a holiday gathering can feel like a mini crisis, as the pressure of preparing a feast for family and friends looms large. This is where my treasured recipe for Martha Stewart’s Make-Ahead Christmas Breakfast Casserole shines. With its comforting layers of hearty sourdough bread, savory pork sausage, and nutty Gruyère cheese, this dish not only saves precious time by allowing you to prepare it ahead of schedule, but it also doubles as a crowd-pleaser that promises to warm hearts and fill bellies. Imagine the joy as this savory casserole puffs up beautifully in the oven, creating a lavish centerpiece for your festive brunch spread. Ready to dive into a holiday breakfast that transforms chaos into culinary triumph? Let’s get cooking!

Why is This Casserole a Holiday Must?
Convenience at Its Finest: Prepare it the night before and let it work its magic in the oven while you handle the holiday rush.
Hearty Flavors: The rich pork sausage and nutty Gruyère meld perfectly, creating a dish everyone will rave about.
Crowd-Pleasing Quality: Serving 8-10, it’s ideal for family gatherings or brunch with friends.
Versatile Options: Feel free to switch up the cheeses or add veggies to suit your guests’ tastes—try it with a mix of cheddar and mozzarella for extra cheesiness!
Comforting Texture: Each slice offers that delightful balance of creamy custard and fluffy bread, ensuring every bite is satisfying.
Breakfast Casserole Ingredients
For the Casserole
- Pork Breakfast Sausage – Adds a savory flavor; substitute with turkey sausage for a lighter option.
- Yellow Onion – Provides depth; shallots can be used for a milder taste.
- Sourdough Bread – This forms the hearty base; ciabatta or whole grain can work well too.
- Gruyère Cheese – Offers a creamy texture; consider Swiss or cheddar for a different flavor.
- Parmesan Cheese – Contributes salty sharpness; Pecorino Romano is a suitable substitute.
- Eggs – Essential for structure; no substitutes work in this case.
- Whole Milk – Adds creaminess; almond milk is a great dairy-free swap.
- Heavy Cream – Enhances richness; half-and-half can be used for a lighter version.
- Dijon Mustard – Imparts a tangy hint; mustard powder is a good substitute.
- Salt – Balances flavors; adjust for dietary needs.
- Black Pepper – Provides subtle heat; white pepper offers a milder taste.
- Ground Nutmeg – Adds warmth; cinnamon can serve as an alternative for a cozy note.
For Serving
- Fresh Fruit Salad – Brightens the brunch table and complements the savory casserole.
- Crispy Bacon – A classic pairing that adds delicious crunch.
This inviting breakfast casserole is perfect for making ahead, allowing you to focus on your festive celebration without missing a beat!
Step‑by‑Step Instructions for Martha Stewart’s Make-Ahead Christmas Breakfast Casserole
Step 1: Prepare the Sausage
In a large skillet over medium heat, add the pork breakfast sausage and diced yellow onion. Cook for about 6-8 minutes, breaking up the sausage with a spoon until browned and fragrant. The onions should turn translucent and slightly caramelized. Once done, remove from heat and set aside to cool slightly.
Step 2: Layer the Bread
While the sausage mixture cools, take a greased 9×13 inch casserole dish and layer the cubed sourdough bread evenly across the bottom. Use about 8 cups of bread cubes, ensuring they cover the bottom in a single layer. This sturdy base will soak up the delicious custard, forming the heart of the Breakfast Casserole.
Step 3: Add Sausage Mixture
Evenly distribute the cooked sausage and onion mixture over the layered bread cubes. Use a spatula to spread it out for consistent coverage, ensuring that each bread cube will absorb those savory flavors. Take a moment to enjoy the aroma of the sausage mingling with the onions—it’s pure comfort!
Step 4: Make Custard
In a large mixing bowl, whisk together 8 eggs, 2 cups of whole milk, 1 cup of heavy cream, 2 tablespoons of Dijon mustard, 1 teaspoon of salt, ½ teaspoon of black pepper, and ¼ teaspoon of ground nutmeg. Whisk until smooth and thoroughly combined; the mixture will be creamy and slightly frothy, ready to blend with the bread layers.
Step 5: Combine
Pour the egg custard mixture generously over the bread and sausage in the casserole dish. Gently press down on the bread cubes with a spatula to ensure they absorb the custard fully. It’s important for the bread to soak in all that rich liquid for optimal texture in your Breakfast Casserole.
Step 6: Add Cheese
Sprinkle 1 cup of grated Gruyère cheese and ½ cup of grated Parmesan cheese evenly over the top of the casserole. The cheeses will create a deliciously melty crust as it bakes, lending both flavor and a beautiful golden finish. Take a moment to admire your layered masterpiece before prepping to chill.
Step 7: Refrigerate
Cover the casserole with plastic wrap or foil and refrigerate for at least 1 hour, or ideally overnight. This resting time allows the flavors to meld beautifully and the bread to absorb the custard mixture thoroughly. Planning ahead means less hassle on the morning of your holiday brunch!
Step 8: Bake
Preheat your oven to 350°F (175°C). Once heated, remove the cover from the casserole and bake for 35-45 minutes, or until the top is puffed and golden brown. The center should be set, and a knife inserted should come out clean. Enjoy the tempting aroma wafting through your kitchen as it bakes!
Step 9: Serve
Allow the Breakfast Casserole to cool for about 10 minutes before slicing and serving warm. This time will help it set up a bit more, making it easier to cut. Pair with a fresh fruit salad or crispy bacon for a festive serving that will delight your guests and make your holiday brunch truly special.

How to Store and Freeze Breakfast Casserole
Fridge: Keep leftover breakfast casserole in an airtight container in the fridge for up to 3 days. This ensures it stays fresh and ready for quick breakfasts.
Freezer: If you want to store it longer, freeze the casserole wrapped tightly in plastic wrap and foil for up to 3 months. Thaw it in the fridge overnight before baking.
Reheating: To reheat, place slices in a preheated oven at 350°F (175°C) for about 15-20 minutes, or until heated through, allowing the flavors to return to their delicious state.
Make-Ahead Option: For the best taste, assemble your breakfast casserole a day in advance and refrigerate it overnight before baking. This enhances the flavors and makes your morning easier!
Tips for the Best Breakfast Casserole
Stale Bread Is Key: Ensure your sourdough bread is slightly stale; it soaks up the custard better, resulting in a softer texture.
Room Temperature Rest: Let the casserole sit for about 30 minutes at room temperature before baking for even cooking and fluffiness.
Watch the Oven: Keep an eye on your casserole towards the end to avoid over-browning. It should be golden and puffed for the best results.
Personalize with Veggies: Don’t hesitate to add sautéed spinach or bell peppers for added nutrition and color in your breakfast casserole.
Cheese Options: Mix up the cheeses; a blend of Gruyère and cheddar offers a delightful twist and extra cheesiness that will please everyone!
Breakfast Casserole Variations & Substitutions
Feel free to put your personal twist on this delightful breakfast casserole and make it truly yours!
- Dairy-Free: Swap whole milk and heavy cream with almond or oat milk for a dairy-free delight. The casserole will still be creamy and satisfying.
- Vegetarian: Replace the pork sausage with a plant-based sausage or sautéed mushrooms and spinach. This variation keeps the heartiness without the meat.
- Herb-Infused: Stir in fresh herbs like thyme or rosemary to elevate the flavor profile of your casserole. This simple addition brings a fresh, aromatic touch to the dish.
- Cheese Swaps: Experiment by mixing Gruyère with cheddar and mozzarella for an even cheesier casserole that oozes deliciousness. Who doesn’t love extra cheese?
- Spice It Up: Add a pinch of cayenne pepper or crushed red pepper flakes for a warming kick. It transforms the cozy flavors into a spicy comfort dish, perfect for festive gatherings.
- Veggie Power: Fold in sautéed bell peppers, zucchini, or kale for added nutrition and a pop of color. Every bite will be packed with flavor and vibrancy!
- Nutty Flavor: Top with chopped pecans or walnuts before baking for a delightful crunch. It adds a nutty flavor that complements the creamy base beautifully.
If you’re looking for more breakfast inspiration, consider trying this dish alongside a fresh winter fruit salad or some crispy bacon to balance the savory elements of your casserole. Need more ideas? Check out Pot Pie Casserole for a hearty meal option to round out your holiday feast!
What to Serve with Martha Stewart Christmas Breakfast Casserole
Imagine a festive holiday table brimming with delightful accompaniments that elevate your hearty casserole into a memorable feast.
- Fresh Fruit Salad: A colorful mix of winter fruits brightens the meal while providing a refreshing contrast to the rich casserole.
- Crispy Bacon: The salty crunch of bacon perfectly balances the creamy texture of the casserole, making it a beloved pairing.
- Maple Syrup Drizzle: Just a hint of maple syrup can add a sweet touch, enhancing the savory flavors of the casserole.
- Herbed Butter Toast: Spread with herbed butter, crisp toast is perfect for scooping up bites of casserole and adds a crispy texture.
- Savory Quiche: A slice of quiche offers another layer of savory goodness that complements the casserole’s hearty flavors.
- Mimosas: Bright and bubbly, this festive drink adds a celebratory mood, balancing the richness of the breakfast casserole.
- Cinnamon Rolls: The warmth of cinnamon rolls warms up the table, inviting guests into a comforting holiday experience.
- Creamy Mashed Potatoes: For brunch enthusiasts, mashed potatoes add a creamy texture that pairs deliciously with egg casseroles.
- Spiced Hot Chocolate: A mug of spiced hot chocolate rounds off the meal with cozy warmth, making it perfect for chilly mornings.
- Gingerbread Cookies: For a sweet treat, gingerbread cookies provide a delightful contrast to the savory casserole, wrapping up the brunch splendidly.
Make Ahead Options
This Martha Stewart Christmas Breakfast Casserole is perfect for busy home cooks who want to enjoy a hearty meal without the morning rush! You can prepare the casserole up to 24 hours in advance by following the first six steps, then cover it tightly with plastic wrap and refrigerate. This allows the flavors to meld beautifully and ensures the bread thoroughly absorbs the custard. When you’re ready to serve, all you need to do is preheat your oven and bake for 35-45 minutes until puffed and golden. This simple make-ahead strategy not only saves you time but also guarantees you’ll have a delicious and festive dish that’s just as delightful as if made fresh that morning!

Martha Stewart’s Make-Ahead Christmas Breakfast Casserole Recipe FAQs
What kind of bread works best for this casserole?
I recommend using slightly stale sourdough bread, as it absorbs the custard beautifully. If you can’t find sourdough, ciabatta or whole grain bread are excellent alternatives that will add a lovely flavor and texture to your casserole.
How should I store leftovers?
Store any leftover casserole in an airtight container in the fridge for up to 3 days. This way, you can easily enjoy delicious breakfasts throughout the week without any hassle!
Can I freeze the breakfast casserole?
Absolutely! To freeze, wrap the assembled casserole tightly in plastic wrap and then in aluminum foil to avoid freezer burn. It can be stored in the freezer for up to 3 months. When you’re ready to eat, thaw it in the fridge overnight and bake as usual. This is a great option for meal prepping!
What should I do if the casserole is soggy?
If you find your casserole is too soggy, it might be due to overly fresh bread or not enough resting time in the fridge. To fix this, try pressing the bread down thoroughly when mixing it with the custard and letting it sit in the refrigerator longer, ideally overnight, for better absorption.
Is this casserole suitable for someone with dietary restrictions?
You can certainly adapt this recipe! For those who are lactose intolerant, substitute the whole milk and heavy cream with almond milk or a dairy-free cream. If you are looking for a lighter option, turkey sausage works well instead of pork sausage. Feel free to adjust depending on your dietary needs!
Can I make this casserole without eggs?
While eggs are essential for binding the casserole together, if you’re looking for alternatives due to allergies or dietary preferences, try using a commercial egg replacer or a mixture of ground flaxseed and water. Use about ¼ cup of flaxseed mixed with ¾ cup of water for every egg. However, please note that this may slightly alter the texture and flavor.

Savory Breakfast Casserole for a Cozy Holiday Brunch
Ingredients
Equipment
Method
- In a large skillet over medium heat, add the pork breakfast sausage and diced yellow onion. Cook for about 6-8 minutes, breaking up the sausage with a spoon until browned and fragrant.
- While the sausage mixture cools, lay the cubed sourdough bread evenly across the bottom of a greased 9x13 inch casserole dish.
- Evenly distribute the cooked sausage and onion mixture over the layered bread cubes.
- In a large mixing bowl, whisk together the eggs, whole milk, heavy cream, Dijon mustard, salt, black pepper, and ground nutmeg until smooth.
- Pour the egg custard mixture generously over the bread and sausage in the casserole dish.
- Sprinkle the Gruyère cheese and Parmesan cheese evenly over the top.
- Cover the casserole and refrigerate for at least 1 hour, ideally overnight.
- Preheat your oven to 350°F (175°C) and bake the casserole uncovered for 35-45 minutes.
- Allow to cool for about 10 minutes before slicing and serving warm.

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