This breakfast casserole recipe is perfect for feeding a crowd. Filled with potatoes and veggies, it's hearty, delicious, and easy to make ahead!

A breakfast casserole is the best way to feed a crowd first thing in the morning. Just ask my mom! She’s been making her famous breakfast casserole recipe on Easter and Christmas morning for as long as I can remember. The rest of my family loves it because it’s hearty and flavorful, packed with potatoes, veggies, eggs, and cheese. My mom loves it because it’s easy to make and—even better—make ahead. She can prep the whole thing the night before and pop it in the oven when guests arrive the next day.

I adapted this breakfast casserole recipe from hers, and it checks all the same boxes.

We love this recipe, and I hope you do as well! It’s perfect for special occasions, but it’s so tasty that you might want it in your regular breakfast rotation too.

What’s In This Easy Breakfast Casserole

This breakfast casserole recipe has 4 main parts:

• Potatoes – Roasted with olive oil, salt, and pepper, they create a starchy, satisfying layer at the bottom of the casserole. I like to use Yukon Gold potatoes here because I love their creamy texture, but russet potatoes work too.
• Sautéed veggies – Yellow onion, garlic, peppers, spinach, and green onions add vibrant color and savory flavor to the casserole.
• Cheddar cheese – It adds richness and salty, nutty flavor. I layer some into the casserole and sprinkle more on top.
• The egg mixture – I whisk the eggs with milk so that they have a delicate, fluffy texture when baked. Use any type of unsweetened milk you like. I’ve successfully made this recipe with whole milk and unsweetened almond milk many times.

Find the complete recipe with measurements below.

Recipe Variations

Like my frittata recipe or crustless quiche, this breakfast casserole is adaptable! Here are a few ways to change it up:

• Vary the veggies. Sautéed broccoli, mushrooms, asparagus, or zucchini would be a nice alternative to the peppers and/or spinach.
• Change the cheese. Pepper jack cheese is a fun replacement for the shredded cheddar. A mix of cheeses works too!
• Switch to sweet potatoes. They’re just as good as regular ones in this hearty breakfast casserole.

How to Make This Breakfast Casserole

This breakfast casserole recipe is easy to make! You can find the complete recipe with measurements at the bottom of this post, but for now, here’s an overview of how it goes:

First, roast the potatoes. Chop them into 1/4-inch cubes. Note: This is small! Smaller cubes=more crisp, golden brown edges. Be careful not to cut them too large.

Place the chopped potatoes on a parchment-lined baking sheet, and toss them with olive oil, salt, and pepper. Roast at 425°F for 20 to 25 minutes, or until tender and browned.

Meanwhile, prep the egg mixture. Whisk together the eggs, milk, and 1/4 teaspoon salt in a large bowl. Set aside.

Next, cook the veggies. Sauté the onion until soft, and then add the peppers and garlic. Cook for 2 minutes before adding the spinach and half the green onions. Cook until the spinach is just wilted.

Then, assemble the casserole. Spread the roasted potatoes at the bottom of an oiled 9×13-inch baking dish. Top with two-thirds of the cheese, followed by the sautéed veggies.

Pour in the egg mixture. Finally, sprinkle the remaining cheese and reserved green onions on top.

Bake the casserole at 350°F until the eggs are set, 40 to 45 minutes. Let stand for 5 minutes before slicing and serving. Enjoy!

Make-Ahead Breakfast Casserole

One of my favorite things about this egg casserole recipe is that you can make it ahead. No need to get up at the crack of dawn in order to have it ready in time for brunch!

Here are two options for prepping it in advance:

Storing and Reheating Leftovers

If you have leftover breakfast casserole, you’re in luck. It reheats perfectly! Store slices in an airtight container in the fridge for up to 3 days, and warm them in the microwave before serving.

You can also freeze this breakfast casserole. Wrap slices tightly in foil or plastic wrap, or seal them in an airtight container. Freeze for up to 3 months. Allow to thaw overnight in the fridge before reheating.

What to Serve with Breakfast Casserole

This easy make-ahead breakfast casserole recipe is flavorful and filling, so you don’t need to pair it with much more than fresh fruit for a satisfying breakfast.

That said, it’s a wonderful addition to a larger brunch. Try pairing it with any of these recipes:

• Cinnamon Rolls
• Banana Bread
• Zucchini Bread
• Coffee Cake

Looking for more brunch ideas? Check out these 51 Best Brunch Recipes!

Breakfast Casserole

Equipment

• 9x13 Baking Dish

Ingredients

For the potatoes

• 3 Yukon Gold potatoes, about 1 pound, chopped into ¼-inch pieces
• 1 tablespoon extra-virgin olive oil
• ½ teaspoon sea salt
• Freshly ground black pepper

For the casserole

• 12 large eggs
• 1 cup milk, any kind
• 1¼ teaspoons sea salt
• 2 tablespoons extra-virgin olive oil, plus more for the baking dish
• ½ medium yellow onion, chopped
• Freshly ground black pepper
• 2 garlic cloves, chopped
• 1 red bell pepper, stemmed, seeded, and chopped
• 1 green bell pepper, stemmed, seeded, and chopped
• 1 cup fresh spinach, roughly chopped
• 4 green onions, chopped
• 1½ cups shredded cheddar cheese

Instructions

• Roast the potatoes: Preheat the oven to 425°F and line a baking sheet with parchment paper. Place the potatoes on the baking sheet. Drizzle with the olive oil and sprinkle with the salt and several grinds of pepper. Toss to coat. Spread evenly on the baking sheet and roast for 20 to 25 minutes, or until tender and browned.
• Make the casserole: Reduce the oven temperature to 350°F and oil a 9x13-inch baking dish.
• In a large bowl, whisk together the eggs, milk, and ¼ teaspoon of the salt. Set aside.
• Heat the olive oil in a large skillet over medium heat. Add the onion, the remaining 1 teaspoon salt, and several grinds of pepper. Cook, stirring occasionally, for 5 to 8 minutes, or until soft. Add the garlic, red pepper, and green pepper and cook, stirring occasionally, for 2 minutes. Add the spinach and half the green onions and toss until the spinach is just wilted.
• Spread the potatoes in an even layer in the prepared baking dish. Top with 1 cup of the cheese, followed by the sautéed veggies. Pour in the egg mixture and sprinkle with the remaining ½ cup cheese and the reserved green onions.
• Bake for 40 to 45 minutes, or until the eggs are set.
• Let stand for 5 minutes before slicing and serving.

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