Easy Breakfast Casserole

Ingredients & Substitutions

Here I explain the best ingredients for my breakfast casserole recipe, what each one does, and substitution options. For measurements, see the recipe card.

• Eggs – For a fluffier breakfast casserole, I recommend room temperature eggs. To lighten it up, swap in egg whites—use 18 whites to replace the 12 whole eggs in my recipe.
• Meat – I used ham, but any cooked meat works great! Try crumbled baked bacon (or turkey bacon), sausage, leftover ham steak, beef (think finely chopped top sirloin), leftover Instant Pot chicken or baked chicken breast, or even chorizo. For a vegetarian option, just skip the meat—it’s still delicious!
• Veggies – I used diced onion, bell peppers, and mushrooms, but this is the perfect opportunity to use up anything you’ve got. Try roasted broccoli or asparagus, sauteed spinach, celery, tomatoes, roasted red peppers, or other leftover roasted vegetables or sauteed vegetables. Cut the veggies to the same size, so they cook at the same rate. For a more hearty breakfast casserole, swap some of the vegetables with roasted potatoes or hash browns, or place a layer of tater tots on top before the cheese.
• Garlic – Fresh minced garlic gives the best flavor, but a tablespoon of jarred garlic or 3/4 teaspoon of garlic powder (mix with the eggs) works, too. You can also chop leftover roasted garlic if you have some.
• Milk Or Cream – Whisking the eggs with half and half makes them light and rich. You can also use regular milk, watered-down heavy cream, coconut milk, or almond milk—whatever you’ve got!
• Cheese – I used sharp cheddar cheese, but any cheese works—mozzarella, American, Swiss, Monterey jack, or pepper jack. You can also omit the cheese (and use a dairy free milk above) if you need that option.
• Olive Oil – For sauteing your meats and veggies. Avocado oil works, too.
• Salt & Pepper – Go light on the salt, as meats and cheeses are already salty. Feel free to toss in some herbs, too: 2 teaspoons of dried (think Italian seasoning) or 2 tablespoons of fresh, like parsley, oregano, or basil.
• Garnish – I used green onions, but fresh herbs are great. For extra flavor, try a drizzle of my blender hollandaise sauce, like I do for eggs benedict casserole.

See below for the formula I use for all my breakfast casserole recipes, so you can use whatever you have on hand!

How To Make A Breakfast Casserole

I have step-by-step photos here to help you visualize the recipe. For full instructions with amounts and temperatures, see the recipe card.

1. Brown the meat. Heat the olive oil in a large skillet (any pan will work, but I prefer a cast iron skillet for nice browning). Add the ham or any meats you’re using, and cook until browned. I recommend medium heat for a cast iron skillet, or medium-high for any other one. Remove and set aside.
2. Saute the vegetables. Add more oil and sauté the onions, until translucent. Add the garlic, bell peppers, and mushrooms (or any veggies) and cook until soft. (If you’re using leftover vegetables that were already cooked, you can skip sauteing them.)

3. Combine the meat and veggies. Remove vegetables from heat and stir in the cooked meat. Transfer the mixture to a greased, large baking dish.
4. Make the egg base. In a large bowl, whisk together the eggs, milk or cream, some cheese, salt, and pepper.

5. Bring it all together. Pour the egg mixture into the baking dish over the meat and veggies and stir to combine. Top with more cheese.

6. Bake your easy breakfast casserole. It’s done when the eggs are set, and the edges are golden brown. Garnish with green onions or fresh herbs if you like.

Make It Ahead

Breakfast casseroles are perfect for making in advance! I’ve got 4 ways you can do it:

• Precook your fillings: Just keep them in the refrigerator separately, and it’s pretty quick to assemble the casserole the day-of.
• Refrigerator: Assemble the casserole, cover tightly with plastic wrap, and refrigerate for 1-2 days. You can bake straight from the fridge, but I recommend letting it sit out for 15-20 minutes first, for more even cooking.
• Freeze before baking: Cover with plastic wrap and foil, and freeze for up to 3 months. Thaw in the fridge overnight before baking.
• Freeze after baking: I don’t love this option for the entire egg casserole recipe, but it’s great for single servings! Wrap portions individually with plastic wrap (or bake smaller portions like my egg muffin cups), pop in a zip lock bag, and freeze for up to 3 months. These do okay reheated from frozen, but are still better if you defrost overnight.

You can bake this easy breakfast casserole as usual if it wasn’t previously baked. For smaller cooked portions, reheat in the microwave or bake for 5-10 minutes at 350 degrees F.

Serving Ideas

My easy breakfast casserole can easily be a quick breakfast all on its own, but for a brunch spread, you can add:

• Potatoes – Serve with roasted potatoes or sweet potato hash (with no added egg) to make your meal more filling. For a lighter option with a similar vibe, try my cauliflower hash browns.
• Bakery favorites – My chocolate chip banana muffins, chocolaty protein donuts, baked oatmeal, or almond flour zucchini bread can all be made ahead.
• Pancakes & waffles – Whip up almond flour pancakes with maple syrup (I prefer natural sugar-free maple syrup), or repurpose similar ingredients to make chaffles.
• Breakfast meats – If you have vegetarian family members, omit the meat from the breakfast casserole recipe itself (replace it with additional veggies), and serve bacon or breakfast sausage on the side for those that want them.
• Salads – My favorite brunch salads are arugula salad and burrata salad.
• Fruit – Throw together a platter of fresh fruit, a sweet acai bowl, or my easy fruit salad.