Easy Spinach Florentine Breakfast Casserole – 45-Minute

This Spinach Florentine Breakfast Casserole is my go-to for weekend mornings when I want something hearty without spending hours in the kitchen. It's a one-pan dish that combines eggs, spinach, mushrooms, and cheese into a fluffy, satisfying bake that feeds a crowd.

The beauty of this casserole is its flexibility. You can assemble it the night before and pop it in the oven the next morning, making it perfect for holiday brunches or lazy Sundays. Plus, it's packed with protein and veggies, so you start your day on the right foot.

I've tested this recipe multiple times to get the perfect texture—creamy, custardy eggs with a golden, slightly crispy top. The key is to not overcook it, and I'll show you exactly how to nail it every time.

About the Ingredients

10 large eggs

The base of the casserole. For a richer flavor, use pasture-raised eggs if available.

1 cup (240ml) whole milk

Adds creaminess. Substitute with half-and-half for extra richness or unsweetened almond milk for a lighter version.

10 oz (280g) frozen chopped spinach, thawed and squeezed dry

Make sure to squeeze out all excess water to avoid a watery casserole. Fresh spinach can be used; sauté it first to wilt and remove moisture.

1 cup (100g) sliced mushrooms (cremini or button)

Adds earthy flavor. Use any mushroom variety you like; shiitake or portobello work well too.

1 small onion, diced (about 1/2 cup)

Adds sweetness and depth. Shallots or leeks are great substitutes.

2 cloves garlic, minced

Fresh garlic gives the best flavor. In a pinch, use 1/2 teaspoon garlic powder.

1 cup (100g) shredded mozzarella cheese

Melts beautifully and gives a nice stretch. Substitute with Swiss, Gruyère, or a blend for different taste.

1/2 cup (50g) grated Parmesan cheese

Adds a salty, nutty flavor. Use Pecorino Romano for a sharper kick.

1/2 teaspoon salt

Enhances flavors. Adjust to taste, especially if your cheese is salty.

1/4 teaspoon black pepper

Freshly ground is best for aroma.

1/4 teaspoon ground nutmeg (optional)

A classic pairing with spinach; adds warmth. Omit if you don't have it.

1 tablespoon olive oil

For sautéing the vegetables. Any neutral oil like canola or avocado works.

Tips & Tricks

• Thaw frozen spinach completely and squeeze out every drop of water. Excess moisture makes the casserole soggy.
• Don't overbake. The center should be just set with a slight jiggle; it will continue to cook from residual heat.
• Let the casserole rest for 5-10 minutes after baking. This allows it to firm up and makes slicing cleaner.

Step-by-Step Instructions

1. Preheat and Prep

Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish with butter or nonstick spray.

2. Sauté Vegetables

In a large skillet, heat olive oil over medium heat. Add onion and mushrooms; cook until softened and lightly browned, about 5-7 minutes. Add garlic and cook for another minute until fragrant.

3. Mix Egg Base

In a large bowl, whisk together eggs, milk, salt, pepper, and nutmeg (if using) until well combined. Stir in the sautéed vegetables, spinach, mozzarella, and Parmesan.

4. Pour into Dish

Pour the mixture into the prepared baking dish, spreading evenly.

5. Bake

Bake for 30-35 minutes, until the edges are golden brown and the center is just set (a knife inserted near the center comes out clean). The internal temperature should reach 165°F (74°C) for food safety.

6. Rest and Serve

Remove from oven and let rest for 5 minutes before slicing. This helps the casserole hold its shape. Serve warm.

Delicious Variations

• Add cooked bacon or sausage for a meatier version.
• Use feta and dill instead of mozzarella and nutmeg for a Greek twist.
• Top with sliced tomatoes and extra cheese before baking for a brunch-y look.

How to Store Spinach Florentine Breakfast Casserole Recipe

Frequently Asked Questions

If you tried this Spinach Florentine Breakfast Casserole, let me know how it turned out in the comments below! And don't forget to share your favorite variations with our community.

Spinach Florentine Breakfast Casserole Recipe

Spinach Florentine Breakfast Casserole: a hearty, cheesy egg bake with spinach and mushrooms, ready in 45 minutes for an easy family breakfast.

★★★★½ 4.8 (127 ratings)

15 minPrep time35 minCook time6Servings285 kcalCalories

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🧂 Ingredients

• 10 large eggs
• 1 cup (240ml) whole milk
• 10 oz (280g) frozen chopped spinach, thawed and squeezed dry
• 1 cup (100g) sliced mushrooms (cremini or button)
• 1 small onion, diced (about 1/2 cup)
• 2 cloves garlic, minced
• 1 cup (100g) shredded mozzarella cheese
• 1/2 cup (50g) grated Parmesan cheese
• 1/2 teaspoon salt
• 1/4 teaspoon black pepper
• 1/4 teaspoon ground nutmeg (optional)
• 1 tablespoon olive oil

📋 Instructions

1. 1Preheat and Prep — Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish with butter or nonstick spray.
2. 2Sauté Vegetables — In a large skillet, heat olive oil over medium heat. Add onion and mushrooms; cook until softened and lightly browned, about 5-7 minutes. Add garlic and cook for another minute until fragrant.
3. 3Mix Egg Base — In a large bowl, whisk together eggs, milk, salt, pepper, and nutmeg (if using) until well combined. Stir in the sautéed vegetables, spinach, mozzarella, and Parmesan.
4. 4Pour into Dish — Pour the mixture into the prepared baking dish, spreading evenly.
5. 5Bake — Bake for 30-35 minutes, until the edges are golden brown and the center is just set (a knife inserted near the center comes out clean). The internal temperature should reach 165°F (74°C) for food safety.
6. 6Rest and Serve — Remove from oven and let rest for 5 minutes before slicing. This helps the casserole hold its shape. Serve warm.

👨‍🍳 Chef's Note: For a lighter version, use egg whites or a combination of whole eggs and egg whites. You can also reduce the cheese by half if you prefer.

Servings: 6

Cuisine: American

Course: Breakfast

Nutrition (per serving): 285 kcal · 12g protein · 22g carbs · 9g fat

Written by Jonas Weber

Jonas writes about technology and digital privacy, translating complex concepts into clear, actionable advice for everyday users. He focuses on practical steps to protect personal data without being paranoid.