Why You’ll Love This Recipe

Easy to prepare and perfect for make-ahead meals.
Packed with protein and nutritious vegetables.
Great for feeding a family or serving at brunch gatherings.
Customizable with different cheeses, vegetables, and proteins.
Reheats beautifully for quick breakfasts throughout the week.
Naturally low in carbohydrates and satisfying.
Delicious for breakfast, brunch, or even dinner.

Ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

Eggs
Fresh spinach
Mushrooms, sliced
Onion, diced
Garlic, minced
Shredded cheddar cheese
Mozzarella cheese, shredded
Milk
Olive oil
Salt
Black pepper
Dried oregano
Fresh parsley for garnish
Optional: cooked bacon, sausage, or ham

Directions

Preheat the oven to 375°F (190°C).
Grease a 9×13-inch baking dish or casserole dish.
Heat olive oil in a skillet over medium heat.
Add the onion and cook until softened.
Stir in the mushrooms and cook until tender and lightly browned.
Add the garlic and cook for about 30 seconds.
Stir in the spinach and cook until wilted. Remove from heat.
In a large mixing bowl, whisk together the eggs, milk, salt, pepper, and oregano.
Stir in the cheddar and mozzarella cheeses.
Add the cooked vegetable mixture and mix until combined.
Pour the mixture into the prepared baking dish and spread evenly.
Bake for 30–35 minutes, or until the center is set and the top is lightly golden.
Allow the casserole to rest for 5–10 minutes before slicing.
Garnish with fresh parsley and serve warm.

Servings and timing

Servings: 8 servings
Prep Time: 15 minutes
Cook Time: 35 minutes
Total Time: 50 minutes

Variations

Add cooked bacon, sausage, or ham for extra protein.
Use feta, Swiss, or goat cheese for a different flavor profile.
Include bell peppers, tomatoes, or zucchini for added vegetables.
Replace spinach with kale or Swiss chard.
Add a pinch of red pepper flakes for a little heat.
Use a combination of wild mushrooms for deeper flavor.
Make it dairy-free by using plant-based milk and cheese alternatives.

Storage/Reheating

Store leftover casserole in an airtight container in the refrigerator for up to 4 days.

To reheat, place individual portions in the microwave for 1–2 minutes or warm in a 350°F (175°C) oven for about 10 minutes until heated through.

You can also freeze the casserole for up to 2 months. Wrap portions tightly and thaw overnight in the refrigerator before reheating.

FAQs

Can I make this casserole the night before?

Yes. Assemble the casserole, cover it, and refrigerate overnight. Bake it the next morning.

What mushrooms work best in this recipe?

Cremini, button, baby bella, and shiitake mushrooms are all excellent options.

Can I use frozen spinach?

Yes. Be sure to thaw and squeeze out excess moisture before adding it to the casserole.

How do I know when the casserole is done?

The center should be fully set, and a knife inserted into the middle should come out clean.

Can I make this recipe low-carb?

Yes. The recipe is naturally low in carbohydrates and fits many low-carb meal plans.

What cheese works best?

Cheddar and mozzarella are popular choices, but Swiss, Gruyère, feta, and Monterey Jack also work well.

Can I freeze leftovers?

Absolutely. The casserole freezes well and can be reheated when needed.

How long does it last in the refrigerator?

Properly stored, it will stay fresh for up to 4 days.

Can I add meat to the casserole?

Yes. Cooked bacon, sausage, ham, or turkey are great additions.

What can I serve with Spinach Mushroom Breakfast Casserole?

Fresh fruit, toast, breakfast potatoes, yogurt, or a simple green salad pair wonderfully with this dish.

Conclusion

Spinach Mushroom Breakfast Casserole is a delicious and versatile recipe that combines wholesome ingredients into a satisfying meal. With its fluffy eggs, savory mushrooms, nutritious spinach, and melted cheese, it’s an easy dish that’s perfect for breakfast, brunch, or meal prep. Whether you’re feeding a crowd or preparing breakfasts for the week ahead, this casserole is sure to become a favorite in your kitchen.

Spinach Mushroom Breakfast Casserole

Print Recipe

5 Stars 4 Stars 3 Stars 2 Stars 1 Star

No reviews

Spinach Mushroom Breakfast Casserole is a hearty and protein-packed dish featuring fluffy eggs, savory mushrooms, fresh spinach, and melted cheese. Perfect for breakfast, brunch, or meal prep, this easy casserole is both satisfying and flavorful.

Author: Laura
Prep Time: 15 minutes
Cook Time: 35 minutes
Total Time: 50 minutes
Yield: 8 servings
Category: Breakfast
Method: Bake
Cuisine: American
Diet: Vegetarian

Instructions

Preheat the oven to 375°F (190°C).
Grease a 9×13-inch baking dish or casserole dish.
Heat olive oil in a skillet over medium heat.
Add the onion and cook until softened.
Stir in the mushrooms and cook until tender and lightly browned.
Add the garlic and cook for about 30 seconds.
Stir in the spinach and cook until wilted. Remove from heat.
In a large bowl, whisk together the eggs, milk, salt, black pepper, and oregano.
Stir in the cheddar and mozzarella cheeses.
Add the cooked vegetable mixture and mix until combined.
Pour the mixture into the prepared baking dish and spread evenly.
Bake for 30–35 minutes, or until the center is set and the top is lightly golden.
Allow the casserole to rest for 5–10 minutes before slicing.
Garnish with fresh parsley and serve warm.

Notes

Frozen spinach may be used if thawed and thoroughly drained.
Add cooked bacon, sausage, or ham for extra protein.
Try Swiss, feta, Gruyère, or goat cheese for different flavor variations.
Store leftovers in the refrigerator for up to 4 days.
Freeze individual portions for up to 2 months and reheat as needed.

Nutrition

Serving Size: 1 serving
Calories: 240 kcal
Sugar: 3 g
Sodium: 520 mg
Fat: 16 g
Saturated Fat: 7 g
Unsaturated Fat: 7 g
Trans Fat: 0 g
Carbohydrates: 5 g
Fiber: 1 g
Protein: 18 g
Cholesterol: 255 mg