Breakfast Sausage Casserole Recipe

This breakfast sausage casserole is the one I make when I need to feed a crowd at breakfast without doing any morning work. You put it together the night before — bread, browned sausage, eggs, milk, cheddar — and stick it in the fridge. Pull it out in the morning, pop it in the oven, and 45 minutes later you’ve got a hot, cheesy, sausage-packed casserole that serves 12. It’s been on our Christmas morning table for years and it’s always the first thing gone.

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A Little Story

This has been on our Christmas morning table for as long as I can remember. It’s one of those recipes that doesn’t need to be reinvented or improved — simple ingredients, assembled the night before, baked the next morning. Everyone eats, nobody is stuck cooking. There’s something really nice about that on Christmas morning especially. The kids are opening gifts, the coffee is on, and the casserole is just doing its thing in the oven.

Why This Recipe Works

The overnight rest is the secret. When you pour the egg mixture over the bread and let it sit refrigerated overnight, the bread fully absorbs everything. By the time it goes in the oven, it’s not sitting on top of liquid — the whole thing has melded together into one cohesive casserole that bakes evenly and slices cleanly.

Dry mustard is the secret ingredient. One teaspoon of dry mustard doesn’t make the casserole taste like mustard — it adds a subtle depth and slight tang that makes the egg mixture taste more complex. Don’t skip it.

Zero morning work. The only thing you do the morning of is pull it from the fridge and put it in the oven. That’s it. Perfect for Christmas morning, Easter brunch, or any time you’re hosting breakfast and want to actually be present instead of cooking.

It feeds a crowd. Full recipe makes about 12 generous servings. Easy to halve for a smaller group.

Ingredients You’ll Need

1 lb breakfast sausage — Brown and drain it before assembling. Sage breakfast sausage is the classic choice and gives the best flavor — I wouldn’t use Italian sausage here, the fennel throws the flavor off. Hot sausage is a great upgrade if your crowd can handle some heat. You can also use ham instead of sausage for a different variation.

8 slices bread — White sandwich bread is traditional and works well. The bread gets buttered, pressed butter-side-down into the dish, and then the egg mixture soaks into it overnight. Day-old bread actually absorbs a little better than fresh because it’s drier. Don’t use anything too hearty like sourdough — it won’t absorb evenly and you’ll get uneven texture.

6 eggs — The base of the custard. Six eggs for a full 9×13 casserole gives you a set, sliceable result. Don’t be tempted to use fewer — it makes the casserole too soft and it won’t hold together when you cut it.

2 cups milk — Whole milk gives you the richest result but 2% works fine. Don’t use skim — the custard will be too thin and won’t set up properly. I’ve tried it with skim once and it came out watery. Not worth the trade-off.

1 teaspoon dry mustard — This is the ingredient people skip and then can’t figure out why their casserole tastes flat. Don’t swap for prepared mustard — the dry version disperses evenly through the egg mixture. It’s a small amount but it genuinely changes the flavor.

1 teaspoon salt — The egg mixture needs seasoning. One teaspoon is the right amount for the full recipe — it seasons everything including the bread.

1 cup grated cheddar cheese — Sharp cheddar gives the best flavor. Grate it yourself if you can — fresh-grated melts into the custard properly, while pre-shredded has an anti-caking coating that makes it clump. Stir it into the egg mixture rather than sprinkling it on top so it’s distributed throughout.

How to Make Overnight Breakfast Sausage Casserole

The Night Before: Assemble the Casserole

Brown and drain your sausage first and let it cool slightly. Butter your bread slices and press them butter-side-down into a greased 9×13 baking dish, covering the bottom. In a bowl, whisk together the eggs, milk, dry mustard, and salt until combined — it’ll look pale yellow and smell faintly eggy, which is exactly right. Stir in the grated cheddar and the browned sausage. Pour this mixture evenly over the bread in the dish. Cover and refrigerate for at least 8 hours — overnight is ideal. Don’t skip the refrigeration; this is the step that makes everything work.

Morning of: Bake and Serve

Pull the dish from the fridge while the oven preheats to 350°. Bake uncovered for 40–45 minutes, until the top is golden brown and the center is set — a knife inserted in the middle should come out clean with no wet egg on it. The casserole will puff up slightly while it bakes and then settle as it cools; that’s normal. Let it rest for 5 minutes before cutting. Don’t skip the rest — cutting into it too early and it falls apart.

Tips for the Best Breakfast Casserole

• Give it the full overnight rest. The minimum is 8 hours, but overnight is better. The bread needs time to fully absorb the egg mixture. If you rush it, the bottom will be soggy and uneven instead of set.
• Drain the sausage well. Excess grease left in the sausage will make the casserole greasy. Brown it, drain it, and let it cool before adding to the egg mixture.
• Don’t skip the butter on the bread. Pressing buttered bread butter-side-down into the dish adds richness and helps prevent the bread from getting too soggy on the bottom during the long overnight soak.
• Check for doneness in the center. The outside will look done before the middle is. Use a knife or toothpick in the very center to make sure it comes out clean before pulling it from the oven.
• Let it rest before cutting. 5 minutes of rest lets the custard firm up enough to slice cleanly instead of falling apart in the pan.

Serving Suggestions

This casserole is the centerpiece of any breakfast spread. It pairs well with:

• Fresh fruit or a simple fruit salad
• Orange juice or a mimosa if it’s that kind of morning
• Toast or pastries on the side
• Hot sauce or salsa on top — it’s great with both

It works for:

• Christmas morning — the classic use case; assemble Christmas Eve, bake while the kids open gifts
• Easter brunch — feeds a crowd, looks impressive, zero morning effort
• Mother’s Day breakfast — set it and forget it so you can actually enjoy the morning
• Weekend brunch with guests — one pan feeds 12 people
• Meal prep — leftovers reheat well for quick weekday breakfasts

Storage and Reheating

Refrigerator: Leftovers keep covered in the fridge for up to 4 days. Reheat individual pieces in the microwave for 1–2 minutes, or warm the whole pan in a 325° oven covered with foil for 15–20 minutes.

Freezer: This casserole freezes well. Bake it first, let it cool completely, then wrap individual portions in plastic wrap and freeze for up to 2 months. Thaw overnight in the fridge and reheat in the microwave or oven.

Make-ahead note: The casserole needs at least 8 hours in the fridge before baking. You can also prep it up to 24 hours in advance — it won’t hurt it to sit an extra night in the fridge.

Variations and Substitutions

Ham version: Swap the sausage for 1–2 cups of diced cooked ham. Great for using up holiday ham leftovers. This is the classic Christmas-morning variation in a lot of families.

Bacon version: Use cooked, crumbled bacon in place of sausage. Gives a smokier flavor. Use about 8–10 slices of bacon.

Add vegetables: Diced bell peppers, chopped onion, or sliced mushrooms can be sautéed and added with the sausage. Dice them small so they distribute evenly.

Cheese swap: Colby jack, Monterey jack, or pepper jack all work in place of cheddar. For more heat, pepper jack is excellent.

Bread swap: Texas toast, thick-cut sandwich bread, or even croissant halves (for a more indulgent version) all work. The thicker the bread, the heartier the casserole.

Gluten-free version: Use gluten-free sandwich bread. Everything else in the recipe is naturally gluten-free.

What to Do With Leftovers

Leftover breakfast casserole reheats really well and makes a great quick weekday breakfast. Microwave a square for about 90 seconds and you’re set. You can also eat it cold straight from the fridge — it’s surprisingly good that way.

If you want to repurpose leftovers: crumble a slice into a skillet with a little butter and crisp it up like a hash. Top with a fried egg and some hot sauce. It’s a completely different (and excellent) way to use up the leftovers.

A Couple Things That Make a Difference Here

This casserole is simple enough that a few details really stand out:

A good 9×13 baking dish. You want even heat distribution so the edges don’t overcook before the center sets. A Pyrex 9×13 with a lid is ideal — it goes from fridge to oven without any stress, and the lid is perfect for the overnight refrigerator step. No plastic wrap fumbling at 11pm.

Sharp cheddar, freshly grated. Pre-shredded cheese is coated with anti-caking agents that prevent it from melting smoothly into the custard. A block of sharp cheddar grated fresh — Tillamook Sharp is consistently good — distributes evenly and melts into the egg mixture the way it should.

Frequently Asked Questions

Can I bake this without refrigerating overnight?

Technically yes, but the texture suffers noticeably. If you’re in a pinch, let it sit for at least 2 hours — the bread needs time to absorb the egg mixture or you’ll get soggy bread floating in liquid rather than a cohesive casserole. Overnight is genuinely worth planning for.

Can I use crescent roll dough instead of bread?

Yes — press unrolled crescent roll dough into the bottom of the baking dish instead of bread slices. It bakes into a flakier, richer base. You can also use canned biscuit dough cut into pieces. Both variations are delicious and honestly a nice upgrade if you want something a little more special.

Can I double this recipe?

Yes — use two 9×13 pans or one very large roasting pan. Double all ingredients. Bake time may need an extra 10–15 minutes for thicker layers — use the knife test in the center to know for sure, not the timer.

My casserole is jiggly in the center — is it done?

A slight jiggle is normal and doesn’t mean it’s undercooked — test with a knife in the center. If the knife comes out clean, it’s done and will firm up as it rests. If the knife comes out with wet, raw egg on it, give it another 5–10 minutes and check again. Don’t pull it just because the timer says so.

Can I make it vegetarian?

Yes — skip the sausage and add diced bell peppers, onion, mushrooms, or spinach. You’ll want about 1–2 cups of vegetables total. Sauté them first to remove excess moisture, otherwise they release water into the casserole as it bakes and the texture gets too wet.

More Breakfast Recipes to Try

• Biscuits and Gravy Casserole
• Easy Bacon and Egg Breakfast Casserole
• Sausage Croissant Breakfast Casserole
• Breakfast Bake Recipe

If you make this breakfast sausage casserole, leave a comment below and let me know how it turned out! And if you added anything different — extra cheese, vegetables, a different meat — I’d love to hear what you did.