This Breakfast Egg Casserole is a baked egg dish made with broccoli, sliced mushrooms, cherry tomatoes, green onion, and shredded cheddar.
It comes together in one baking dish, sets up firm enough to slice cleanly, and works just as well reheated from the fridge on a Tuesday as it does fresh out of the oven.
It earns its spot in a meal prep rotation. Good for Sunday brunch with guests, easy enough for a regular weekday setup, and flexible enough to swap whatever vegetables you have on hand.
I like serving it alongside Egg Muffins with Spinach and Bacon for a bigger spread, or keeping it simple with toast and a cup of coffee.
If you’re into easy egg-based breakfast recipes, these are worth bookmarking too:
- Egg Muffins with Spinach and Bacon
- Homemade Eggs Omelet Rolls With Cream Cheese And Parsley
- Healthy Vegetable Muffins with Carrot and Broccoli
- 10+ Low Carb Breakfast Ideas
Ingredients You’ll Need
The vegetables here are broccoli, mushrooms, cherry tomatoes, and green onion, but the recipe is flexible. The one non-negotiable is sauteing the mushrooms before assembly.
They release a lot of liquid, and if you skip that step the casserole will be watery and won’t set properly.
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Ingredients
8 large eggs
1/2 cup whole milk
1 cup broccoli florets, finely chopped
1 cup cremini mushrooms, sliced
1 cup cherry tomatoes, halved
3 green onions, thinly sliced
1 cup shredded cheddar cheese
1 tablespoon olive oil
1/2 teaspoon salt
1/4 teaspoon black pepper
1/2 teaspoon garlic powder
Directions
- Preheat your oven to 375 degrees F and lightly grease a 9×13 inch baking dish with oil or butter.
While the oven heats, chop the broccoli into small pieces, no bigger than half an inch.
Larger pieces won’t cook through evenly surrounded by egg, so keep them small and even.
Slice the mushrooms, halve the cherry tomatoes, and thinly slice the green onions. Set everything aside. - Heat the olive oil in a skillet over medium heat.
Add the broccoli and mushrooms and cook, stirring occasionally, for about 5 to 6 minutes until the mushrooms have released their moisture and the broccoli is just starting to soften.
You don’t want them fully cooked at this point, just with the raw edge taken off.
Season lightly with a pinch of salt and remove the pan from the heat. This step keeps the casserole from going watery during baking. - Crack the 8 eggs into a large bowl and add the milk, salt, black pepper, and garlic powder.
Whisk until the yolks and whites are fully combined and the mixture looks uniform.
Don’t over-whisk to the point of heavy foam, just enough to blend everything smoothly.
Taste the mixture and adjust seasoning now. It’s harder to correct once the casserole is baked. - Spread the sauteed broccoli and mushrooms evenly across the bottom of the prepared baking dish.
Scatter the halved cherry tomatoes and sliced green onions over the top.
Pour the egg mixture evenly over the vegetables, making sure it distributes into all the gaps.
Sprinkle the shredded cheddar cheese evenly over the entire surface. Don’t press it down. - Place in the preheated oven and bake for 30 to 35 minutes, until the center is set and doesn’t jiggle when you gently shake the dish.
The edges will be golden and slightly pulled away from the sides of the pan.
Insert a knife in the center and it should come out clean, not wet.
If the cheese starts to brown too quickly, cover loosely with foil for the last 10 minutes.
Don’t pull it too early. The center looks slightly underdone right before it finishes, and carryover heat does the rest. - Pull the casserole from the oven and let it rest for at least 5 minutes before slicing (I know it’s hard, but it matters).
Resting lets the egg finish setting so it cuts cleanly without falling apart.
Run a sharp knife along the edges first, then cut into squares and serve warm straight from the baking dish.
- Serve u0026 Enjoy! Serve warm straight from the baking dish.
Important Recipe Notes
- Chop the broccoli small: Pieces larger than half an inch won’t cook through evenly when surrounded by egg. Small, even pieces soften properly during the 30-35 minute bake without turning mushy at the edges.
- Always saute the mushrooms first: Mushrooms release a significant amount of water as they cook. Adding them raw to the casserole pushes all that liquid into the egg mixture, and the result is a loose, watery casserole that won’t set properly. Five to six minutes in a hot pan with a bit of oil is all it takes.
- The center will look slightly underdone at 30 minutes: That’s expected. The egg continues to set from carryover heat after you pull it from the oven. If the knife test still comes out wet at 35 minutes, give it another 5 and check again. Overbaking dries it out, so check early.
- Make-ahead: Assemble the entire casserole the night before, cover tightly with plastic wrap, and refrigerate unbaked. Pull it out 20 minutes before baking to take the chill off, then bake as directed. It may need an extra 5 minutes coming from cold.
- Storage: Refrigerate leftovers tightly covered for up to 4 days. Reheat individual portions in the microwave for 60 to 90 seconds, or cover the whole dish with foil and warm at 325 degrees F for about 15 minutes.
How to Serve, Store & Customize This Recipe
Serving: This casserole works as the centerpiece of a weekend brunch or as a make-ahead weekday breakfast. Serve warm with toast, fresh fruit, or a simple green salad. It also holds at room temperature for about an hour, which makes it practical for buffet setups where it needs to sit out for a bit.
Storing: Leftovers keep well covered in the fridge for up to 4 days. Reheat individual slices in the microwave for 60 to 90 seconds, or warm the whole dish at 325 degrees F with foil on top for about 15 minutes. The texture stays good on day two and three, though it softens slightly from the first day.
Customizing: The vegetables are flexible. Swap the cherry tomatoes for diced bell peppers or sun-dried tomatoes, and use any shredded cheese you like. A sharp white cheddar or mozzarella both work well. For a richer version, substitute half the milk with heavy cream. You can also fold in cooked crumbled sausage or diced ham if you want a meatier version.
Breakfast Egg Casserole
Course: Recipes6
servings15
minutes35
minutes220
kcalIngredients
8 large eggs
1/2 cup whole milk
1 cup broccoli florets, finely chopped
1 cup cremini mushrooms, sliced
1 cup cherry tomatoes, halved
3 green onions, thinly sliced
1 cup shredded cheddar cheese
1 tablespoon olive oil
1/2 teaspoon salt
1/4 teaspoon black pepper
1/2 teaspoon garlic powder
Directions
- Preheat oven to 375F and grease a 9×13 baking dish. Chop broccoli small (under 1/2 inch), slice mushrooms, halve cherry tomatoes, and slice green onions.
- Saute broccoli and mushrooms in olive oil over medium heat for 5-6 minutes until mushrooms release their liquid and broccoli softens slightly. Season with a pinch of salt.
- Whisk eggs with milk, salt, pepper, and garlic powder until fully combined.
- Spread sauteed vegetables in the baking dish, scatter cherry tomatoes and green onions on top, pour egg mixture over everything, and top with shredded cheddar.
- Bake 30-35 minutes until center is set and a knife inserted in the middle comes out clean. Cover with foil if cheese browns too quickly.
- Rest 5 minutes before slicing, then serve warm straight from the dish.
Notes
- For a make-ahead version, assemble the casserole the night before, cover tightly, and refrigerate overnight. In the morning, let it sit at room temperature for 15–20 minutes before baking.
- Use cooked sausage, bacon, ham, turkey, or shredded chicken for extra protein. For a vegetarian version, skip the meat and add more vegetables or a little cottage cheese.
- For a keto or low-carb casserole, avoid potatoes, bread, or hash browns and use eggs, cheese, meat, and low-carb vegetables.
