Sausage and Egg Breakfast Casserole

With lots of eggs, vegetables, and breakfast sausage, this sausage and egg breakfast casserole has lots of flavors and is a great, filling breakfast experience. Easy to make ahead of time, this infinitely customizable breakfast dish is great for easy holiday or anytime meals to feed a family.

A good breakfast casserole is a great meal. Easy to throw together and you can make it the night before; these kinds of dishes are great for an easy breakfast or brunch. What makes these dishes even better is how customizable they are.

Great using leftovers after holidays, or to make the night before a holiday, a breakfast casserole is simple to toss together. This sausage and egg breakfast casserole is perfect for Christmas, Easter, or Mother’s Day morning.

Meat – I like to use a 1-pound package of breakfast sausage here and I went with country mild. You could easily use another flavor like sage, maple, hot, etc., or even use sausage links and cook and slice them into pieces. Other good options include Italian sausage, chicken sausage, bacon, turkey bacon, or anything else you enjoy.

Starch – You want a starch option that can soak up some of the moisture in this dish so that it doesn’t come out runny. I made this version with frozen, diced hashbrowns, but you could also use shredded hashbrowns or stale bread cubes.

Vegetables – Classically you could make this with just breakfast sausage and onion, but I like to add more flavors and textures. For this version of breakfast casserole, I use a combination of yellow onion, a bit of garlic, green and red bell peppers, and spinach.

Seasoning – I keep the seasoning here simple with just some kosher salt, black pepper, and a bit of mustard powder. This gives the taste a slight tang but does not make it take mustardy at all. You could also swap fresh garlic with garlic powder or add some crushed red pepper for more heat.

Liquid – For the eggy liquid that binds everything together, I use a full dozen large eggs and some half-and-half. You could also use whole milk or heavy cream if you wish. While a dozen eggs seem like a lot, keep in mind this does make 12 portions, so it feeds a lot of people.

Cheese – I like to mix cheese into the casserole and then top it with more near the end of baking. Depending on how cheesy you want the dish to be, use anywhere from 1-2 cups of shredded cheese. The cheese is up to you as well. I used sharp cheddar for the flavor, but you could use any melty cheese or a mix of cheddar, gouda, mozzarella, Monterey Jack, Colby, provolone, etc.

Start with a large skillet or braising pan set over medium heat on the stovetop. Add a little oil and place the breakfast sausage in the pan. Using a wooden spoon or fork, work on breaking up the sausage and moving it around.

Continue breaking it up and stirring it as it cooks until no pink spots remain and the sausage is crumbled into smallish pieces, about 8-10 minutes. Transfer the sausage to a paper towel lined plate to drain off some of the fat and set aside for now.

This next part can be done in two different ways, so it’s your choice here. Add the hashbrowns to the dish raw or precook them. Both ways are fine, but I like to toast them up a bit myself.

Mix the salt and pepper together and set aside. In the same pan you cooked the sausage in, melt some butter and then add the frozen hashbrowns and turn the heat to medium-high. Add a pinch or two of salt and pepper, stir the hash browns so they’re coated in the melted butter, and add another pinch of salt and pepper.

Now spread out the hashbrowns into a single, even layer and let them cook for 5 minutes without disturbing them. Flip them over and cook for another 5 minutes to brown on the other side. Give them a stir and transfer them to a 13x9 baking dish or a deep casserole dish and set them aside.

If you don’t want to pre-cook the hashbrowns, you should thaw them overnight in the refrigerator the day before or leave them out at room temperature for an hour or so. Dump them onto some paper towels and use more paper towels to dry them off as much as possible. Now add them to the bottom of the baking dish as above.

Add some more butter or oil to your skillet if needed and now add the diced onion. Sauté for 2-3 minutes, then add the diced bell pepper to the skillet. Season with a pinch or two of salt and pepper and continue cooking until the onions turn translucent and the peppers have softened. About 5-6 minutes longer.

Finally, add the minced garlic, the cooked sausage, and the spinach to the pan. Stir everything together and cook for 1-2 minutes, until the spinach has wilted and shrank. Set everything aside to cool down a bit.

Make the Custard & Layer the Dish

In a large mixing bowl, add all 12 eggs and whisk together until there’s no visible streaks of yolks or whites. Pour in half-and-half (or other milk/cream), the remaining salt and pepper, and the mustard powder. Whisk again until fully combined and set aside.

Once the filling has cooled a bit, begin layering it into the baking dish with the potatoes. Add half the mixture to the baking dish on top of the potatoes. Sprinkle in about ⅔ of shredded cheddar and then top with the rest of the sausage mixture.

Now pour the egg batter evenly over everything else. From here, you can cover and refrigerate overnight or cook immediately. If you use bread instead of hashbrowns, I recommend the overnight soak. Using potatoes makes this optional.  

Bake the Casserole

Preheat the oven to 350°F / 180°C.

If cooking the casserole immediately, cover the baking dish with foil and place onto center rack in the oven. If cooking it the next morning, let it sit at room temperature for 15-20 minutes before baking.

Bake, covered, for about 40 minutes. Remove from the oven and uncover. Sprinkle on the remaining cheese and return to the oven. Continue baking for another 15-20 minutes. The center should just barely jiggle, and the cheese should be melted and slightly browned.

Remove from the oven and set aside to cool a bit. You should give it at least 15 minutes and up to 30 minutes or more to cool and set.

Optionally top with some freshly chopped parsley or green onion, cut into 12 portions, and serve warm.

Protein – Breakfast sausage is great and a classic, but you can use almost anything here. Consider things like Italian sausage, ground pork, bacon, pulled pork, chicken sausage, turkey bacon, ground turkey, ground beef, pulled beef, brisket, or cooked ham.

Vegetables – I love the combination of peppers and onions, but you can use a lot of other options here just fine. A few popular choices include kale, broccoli, brussels sprouts, asparagus, leeks, green onions, zucchini, squash, cherry tomatoes, and mushrooms. Try to keep whatever mixture you use to 3-4 cups of vegetables though, not counting the potatoes.

Using Bread – Another popular way to make breakfast casserole is with stale bread instead of hash browns. For this style, use about 6-ounces of bread (roughly 4-6 cups) cut into about ½-inch cubes. Good options for bread include brioche, challah, and sourdough. Some people use white sandwich bread, but that’s personally my last choice if you have options.

To stale the bread, I leave it out in the morning on the day I’m going to make the dish and by the evening it should be stale to make the dish. Alternatively, you can toast the cubed bread in a 300°F oven for about 10 minutes. Make the casserole as directed, simply swapping the bread for the potatoes.

Spicy Breakfast Casserole – If you love food with some kick, try this spicy spin. Use a hot breakfast sausage, or hot Italian or even chorizo. Replace the green bell pepper with a jalapeno or serrano and add ¼ - ½ teaspoon of crushed red pepper to the seasoning.

Vegetarian Breakfast Casserole – If you want to make a meatless version, omit the sausage. Ramp up the amount of vegetables you use to 4-4 ½ cups and consider some of the vegetables I mention just above here. A good option would be onion, red bell pepper, baby spinach or kale, broccoli florets, and mushrooms.

Baking Dish – I absolutely love my Staub 13x9 enameled baking dish. Some casserole dishes are a bit small in my opinion, but this baking dish is durable, easy to clean, and deeper than most other brands. This helps make casserole dishes and mac-and-cheese easier since the food actually fits inside.

Braising Pan – I love my enameled braising dish because it’s a great cooking dish that’s between a large skillet and a Dutch-oven. About as wide as a large skillet with higher walls and comes with a lid and can be used on the stove or inside the oven.

Cheese Grater – I love this tool for shredding my own cheese at home. While you can do the same on a box grater, it gets difficult near the end to finish shredding and grating things without cutting yourself. A rotary cheese grater makes short work of shredding cheese and is also useful for grating frozen butter for various recipes as well.

❄️ How to Store Breakfast Casseroles

Once your sausage and egg breakfast casserole has cooled completely, cover the dish with plastic wrap and refrigerate for 3-4 days. Alternatively, if you don’t have a lot of leftovers, transfer to an airtight container so it takes up less space in your fridge.

To reheat, you can simply microwave small portions for 30-45 seconds, until heated through. If reheating large amounts, place in a 350°F oven for 20 minutes or so.

For longer storage, you can also freeze leftovers. Wrap portions or the entire dish in plastic wrap and a layer of aluminum foil and then freeze for up to 3 months. Thaw overnight in the refrigerator. You can also prep ahead of time by making the dish, not baking, and freeze for up to 3 months.