This savory spinach and mushroom breakfast casserole is a great way to start your day, and it makes a great option for an easy dinner too!
Why this Recipe Works
Breakfast casserole is an easy way to make breakfast for a crowd. They can often be prepared ahead and refrigerated, then baked the next morning. So they are perfect for the holidays when you have guests.
This breakfast casserole with spinach and mushrooms is a perfect example. You can cook your veggies and assemble the dish then cover and refrigerate overnight. Throw it in the oven the next morning, and you're done!
For another delicious breakfast casserole option, check out my hashbrown and sausage breakfast casserole too!
- Fresh spinach - you can substitute frozen, but make sure to thaw and drain it very well to remove any excess moisture.
- Mushrooms - white button mushrooms or cremini are both great options.
- Cheese - I use mild cheddar in this dish, but gruyere or crumbled feta are also great options.
See the recipe card at the bottom of this post for a full list of ingredients and measurements.
How to Make Breakfast Casserole
This spinach breakfast casserole is simple to make in just a few easy steps:
- Melt the butter in a large sauté pan over medium heat and add in the mushrooms and onions. Cook until the onions are softened and the mushrooms are browned and sizzling, around 4 to 5 minutes. Then add in the spinach and cook for another 1-2 minutes until wilted.
- Transfer the vegetables to a greased 9 by 13 baking dish and top with 1 cup of shredded cheese.
- In a large bowl whisk together the eggs, half and half, salt and pepper then pour over the vegetable mixture. Sprinkle the remaining cheese on top. Bake in a 350ºF oven for around 30 to 35 minutes until set. Allow the casserole to cool for 10 minutes before serving.
What to serve with breakfast casserole
This savory breakfast casserole is similar to quiche florentine and makes a hearty and filling, so it's great on its own. But it's also a great option to serve as part of a breakfast or brunch spread for Easter or Mother's Day.
It would be excellent served alongside a sweet dish like my brioche french toast casserole, cinnamon french toast sticks, lemon blueberry pancakes, or glazed blueberry biscuits and a platter of breakfast meats like bacon and sausage.
Storage and reheating instructions
Store leftovers in an airtight container and refrigerate for up to 4 days. Reheat in the microwave until warmed through.
You can also freeze the cooked casserole for up to 3 months. To reheat, thaw in the refrigerator overnight and heat in a 350ºF oven until warmed through, around 15-20 minutes.
Spinach Mushroom Breakfast Casserole
- 1 cup onion, diced
- 3 Tablespoons butter
- 8 ounces fresh mushrooms, sliced
- 5 ounces fresh spinach
- 1½ cups shredded cheddar cheese
- 12 large eggs
- 1½ cup half and half
- 1 teaspoon Kosher salt
- ½ teaspoon black pepper, freshly ground
- Preheat oven to 350°F
- Melt butter in a large sauté pan over medium heat then add the diced onion and sliced mushrooms. Cook, stirring occasionally, until the mushrooms are browned and sizzling, around 4-5 minutes. Add the spinach and cook until wilted.
- Add the vegetable mixture to a greased 9 by 13 baking dish and top with 1 cup of the cheese.
- Whisk the eggs, salt, pepper, and half and half together in a large bowl then pour over the vegetable mixture. Sprinkle the remaining ½ cup of cheese over top.
- Bake for around 30-35 minutes until set. Let cool for 10 minutes before serving.
* All nutrition information we provide are estimates based on third party calculators. We encourage you to calculate these on your own for accurate results.