Spinach and Mushroom Breakfast Casserole
A protein-rich, make-ahead breakfast casserole combining earthy mushrooms, vibrant spinach, and eggs that solves the morning rush dilemma while delivering exceptional flavor and nutrition.
Equipment
- 9x13-inch Baking Dish
- Large Skillet
- Mixing Bowls
Ingredients
Main Ingredients
- 10 large eggs
- 1 cup milk whole or plant-based alternative
- 8 oz mushrooms sliced (cremini or white button)
- 6 cups fresh spinach roughly chopped (or 10 oz frozen spinach, thawed and drained)
- 1 medium onion diced
- 3 cloves garlic minced
- 1½ cups shredded cheese sharp cheddar, Gruyère, or a blend
- ¼ cup Parmesan cheese freshly grated
Seasonings and Oil
- 2 tablespoons olive oil
- 1 teaspoon dried thyme
- ½ teaspoon red pepper flakes optional
- salt and freshly ground black pepper to taste
- butter or cooking spray for greasing
Instructions
- Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with butter or cooking spray.
- Heat olive oil in a large skillet over medium heat. Add diced onions and cook until translucent, about 3-4 minutes.
- Add garlic and cook for another 30 seconds until fragrant.
- Add sliced mushrooms to the onion mixture and cook until they release their moisture and begin to brown, approximately 5-7 minutes. Season with thyme, salt, and pepper.
- Add fresh spinach to the skillet (you may need to do this in batches). Cook until just wilted, about 1-2 minutes. If using frozen spinach, ensure it's completely thawed and squeeze out excess moisture before adding to the pan. Remove the vegetable mixture from heat and let cool slightly.
- In a large bowl, whisk together eggs and milk until well combined. Season with salt, pepper, and red pepper flakes if using.
- Spread half of the vegetable mixture in the prepared baking dish. Sprinkle with half of the shredded cheese.
- Add the remaining vegetables and top with the rest of the shredded cheese. Pour the egg mixture evenly over the vegetables and cheese. Sprinkle Parmesan cheese on top.
- Bake in the preheated oven for 40-45 minutes, or until the center is set and the top is golden brown. A knife inserted in the center should come out clean.
- Allow to rest for 10 minutes before serving.
Notes
This casserole can be assembled the night before and refrigerated. Add 5-10 extra minutes to baking time when cooking from cold.
For meal prep, cut into individual portions and refrigerate for up to 4 days or freeze for up to 3 months.
The casserole actually improves in flavor after a day in the refrigerator as the herbs and seasonings meld together.
Nutrition
Calories: 225kcalCarbohydrates: 6gProtein: 18gFat: 15gSaturated Fat: 6gFiber: 2gVitamin A: 75IUCalcium: 30mgIron: 15mg
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