The Veggie Breakfast Casserole with Spinach and Mushrooms is the ultimate breakfast dish for anyone who loves a nourishing, hearty, and flavor-packed start to the day. This vegetarian twist on the classic breakfast casserole is filled with vibrant vegetables, fluffy eggs, and gooey cheese, creating a comforting meal that feels indulgent yet wholesome.

Each bite bursts with the earthiness of sautéed mushrooms, the freshness of spinach, and the creaminess of melted cheese — all baked together to golden perfection. It’s ideal for meal prepping, feeding a crowd, or simply treating yourself to a cozy breakfast that’s both healthy and satisfying.

Why I Love This Recipe

I love this recipe because it perfectly balances comfort and nutrition. The combination of tender spinach, caramelized onions, and savory mushrooms gives it a rich, umami depth — without the need for meat.

It’s light enough to enjoy any day of the week, yet filling and flavorful enough to stand on its own as a complete meal.

Why It’s a Must-Try Dish

This veggie breakfast casserole is a must-try because it’s a crowd-pleaser that checks all the boxes — delicious, healthy, and easy to prepare. It’s packed with protein and fiber, naturally gluten-free (if you skip the bread layer), and a fantastic way to get your greens in the morning.

Whether you’re cooking for a brunch party or meal-prepping for the week, it’s the kind of dish that feels both wholesome and special.

Recipe Details

• Preparation Time: 20 minutes
• Cooking Time: 45 minutes
• Total Time: 1 hour 5 minutes
• Servings: 6–8
• Calories: ~290 kcal per serving
• Course: Breakfast / Brunch
• Cuisine: American

Ingredients

Main Ingredients

• 8 large eggs
• 1 cup milk (whole or 2%)
• 1 tablespoon olive oil or butter
• 2 cups fresh spinach, chopped
• 1 ½ cups mushrooms, sliced (cremini, button, or portobello)
• 1 small onion, diced
• 1 bell pepper (red or yellow), diced
• 1 cup shredded cheddar cheese (or mozzarella or Swiss)
• ½ teaspoon garlic powder
• ½ teaspoon onion powder
• ½ teaspoon dried thyme (or Italian seasoning)
• Salt and pepper, to taste

Optional Add-ins

• ½ cup cherry tomatoes, halved
• ¼ cup feta or goat cheese (for extra creaminess)
• 1 small zucchini, diced
• ¼ cup chopped green onions or parsley (for garnish)

Cooking Directions

Step 1: Preheat Oven

Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking dish with olive oil, butter, or non-stick spray.

Step 2: Cook the Vegetables

• In a large skillet over medium heat, add olive oil or butter.
• Sauté onions and bell peppers for about 3 minutes, until softened.
• Add mushrooms and cook until they release their moisture and begin to brown (5–6 minutes).
• Add spinach last and cook just until wilted.
• Season with salt, pepper, and dried thyme. Remove from heat and set aside to cool slightly.

Step 3: Prepare the Egg Mixture

In a large mixing bowl, whisk together eggs, milk, garlic powder, onion powder, salt, and pepper until smooth and frothy.

Step 4: Assemble the Casserole

• Spread the sautéed vegetables evenly in the greased baking dish.
• Sprinkle shredded cheese evenly over the veggies.
• Pour the egg mixture on top, ensuring all ingredients are coated evenly.
• Optionally, sprinkle some feta or goat cheese on top for added flavor.

Step 5: Bake the Casserole

• Place the dish in the oven and bake for 40–45 minutes, or until the eggs are set in the center and the top is golden brown.
• Check by inserting a knife in the center — it should come out clean.

Step 6: Cool and Serve

Let the casserole rest for 5–10 minutes before slicing. Garnish with chopped herbs or green onions before serving.

Step-by-Step Preparation Summary

1. Preheat oven to 350°F (175°C).
2. Sauté onions, peppers, and mushrooms until tender.
3. Add spinach and cook until wilted.
4. Whisk eggs, milk, and seasonings together.
5. Layer veggies and cheese in a baking dish.
6. Pour egg mixture over and bake for 40–45 minutes.
7. Cool, slice, and serve warm.

How to Serve

Serve this veggie breakfast casserole warm, either on its own or with sides such as:

• Whole-grain toast or avocado toast
• Fresh fruit salad or roasted potatoes
• A dollop of Greek yogurt or salsa for a tangy contrast
• Hot coffee, tea, or fresh orange juice for a balanced breakfast

This casserole also makes a great lunch or light dinner paired with a green salad.

Recipe Tips

• Use fresh vegetables: They give better texture and flavor than frozen.
• Drain excess liquid: After cooking the mushrooms and spinach, make sure to drain excess moisture to avoid a soggy casserole.
• Add spices: Paprika, cumin, or chili flakes can add an extra kick.
• Don’t overbake: Remove as soon as the center is set — overbaking makes it rubbery.
• Reheat gently: Warm slices in the oven at 325°F for best results.

Variations

• Cheesy Broccoli Casserole: Substitute spinach with steamed broccoli florets and top with extra cheddar.
• Mediterranean Style: Add sun-dried tomatoes, olives, and feta cheese.
• Mexican Twist: Add diced jalapeños, black beans, and pepper jack cheese; serve with salsa.
• Vegan Version: Replace eggs with a chickpea flour and plant milk mixture, and use vegan cheese.
• High-Protein Option: Mix in cottage cheese or Greek yogurt into the egg mixture before baking.

Freezing and Storage

• Storage: Refrigerate leftovers in an airtight container for up to 4 days.
• Freezing (Baked): Slice cooled casserole into portions, wrap individually, and freeze for up to 2 months. Reheat in oven or microwave.
• Freezing (Unbaked): Assemble the casserole (without baking), cover tightly, and freeze for up to 1 month. Thaw overnight before baking.

Special Equipment Needed

• 9×13-inch baking dish
• Large skillet
• Mixing bowl
• Whisk
• Spatula
• Oven mitts

FAQ

Q: Can I use frozen spinach?
A: Yes, but make sure to thaw and squeeze out all excess water to avoid sogginess.

Q: Can I prepare it the night before?
A: Absolutely! Assemble the casserole, cover it, and refrigerate overnight. Bake fresh in the morning.

Q: Can I add potatoes?
A: Yes — diced or shredded hash browns make a great addition for a heartier casserole.

Q: What cheese works best?
A: Cheddar, mozzarella, Swiss, or feta are excellent choices depending on your flavor preference.

Q: How do I make it dairy-free?
A: Use almond or oat milk instead of regular milk and substitute vegan cheese.

Conclusion

The Veggie Breakfast Casserole with Spinach and Mushrooms is a perfect example of how simple ingredients can create something truly delicious. It’s hearty yet light, healthy yet comforting, and endlessly versatile. Whether you’re feeding a family, meal prepping for the week, or hosting brunch, this casserole will win everyone over with its wholesome flavors and vibrant colors.

With every bite, you’ll taste the warmth of sautéed veggies, the creaminess of cheese, and the richness of eggs — a breakfast worth waking up for!