Easy Egg Casserole with Avocado – 45-Minute Brunch

I first discovered the magic of egg casseroles on a chilly morning in a small Vermont inn, where the innkeeper served a bubbling dish straight from the oven. The aroma of eggs, cheese, and herbs filled the room, and every bite was pure comfort. That memory stuck with me, and I've since recreated that warmth in my own kitchen, adding a fresh twist that makes it perfect for any gathering.

This egg casserole is my go-to for lazy weekend brunches and holiday mornings alike. It's simple enough for a weekday breakfast but impressive enough for guests. The beauty lies in its versatility – you can use whatever veggies you have on hand, and the creamy avocado on top adds a bright, fresh contrast to the rich, savory casserole.

Whether you're feeding a crowd or meal-prepping for the week, this dish delivers. It's a one-pan wonder that comes together quickly, bakes to perfection, and leaves everyone satisfied. Let's get started!

About the Ingredients

8 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 or a dairy-free milk like oat milk.

1/2 cup (60g) shredded cheddar cheese

Sharp cheddar adds a punch. Try Gruyère or Monterey Jack for a different taste.

1/4 cup (30g) grated Parmesan cheese

Adds a savory, nutty note. Pecorino Romano works well too.

1/2 cup (75g) diced red bell pepper

Adds sweetness and color. Any bell pepper color is fine.

1/2 cup (75g) diced green bell pepper

Provides a fresh, slightly bitter contrast. Swap for zucchini or spinach.

1/4 cup (40g) finely chopped red onion

Adds a mild bite. Use yellow onion or shallots if preferred.

2 tablespoons chopped fresh parsley

Brightens the dish. Fresh chives or dill are great alternatives.

1/2 teaspoon salt

Enhances flavors. Adjust to taste, especially if using salty cheese.

1/4 teaspoon black pepper

Adds a subtle kick. Freshly ground is best.

1 avocado, sliced

For serving. Choose a ripe avocado that yields slightly to pressure.

Tips & Tricks

• Don't overmix the eggs – a few streaks are fine, as overmixing can make the casserole tough.
• Use a glass or ceramic baking dish for even cooking and easy cleanup.
• Let the casserole rest for 5 minutes after baking so it sets properly and slices cleanly.

Step-by-Step Instructions

1. Preheat oven

Preheat your oven to 350°F (175°C). Grease an 8×8-inch (20×20 cm) baking dish with butter or non-stick spray.

2. Whisk eggs

In a large bowl, whisk the eggs and milk until well combined and slightly frothy. This incorporates air for a lighter texture.

3. Add ingredients

Stir in the cheddar, Parmesan, bell peppers, red onion, parsley, salt, and black pepper. Mix until evenly distributed.

4. Pour into dish

Pour the egg mixture into the prepared baking dish and spread it evenly.

5. Bake the casserole

Place in the preheated oven and bake for 30-35 minutes, or until the center is set and the top is golden brown. A knife inserted into the center should come out clean.

6. Rest and serve

Remove from the oven and let rest for 5 minutes. Slice into squares and serve topped with fresh avocado slices.

Delicious Variations

• Add cooked crumbled sausage or bacon for a meaty version.
• Swap the bell peppers for sautéed mushrooms and spinach for an earthy twist.
• Use feta and sun-dried tomatoes for a Mediterranean flair.

How to Store Egg Casserole with Avocado

Frequently Asked Questions

I hope this egg casserole brings as much joy to your table as it does to mine. Give it a try and let me know how it turns out in the comments below!

Egg Casserole with Avocado

This hearty egg casserole is packed with veggies and cheese, baked until golden, and served with fresh avocado for a satisfying brunch.

★★★★½ 4.8 (127 ratings)

15 minPrep time35 minCook time6Servings285 kcalCalories

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🧂 Ingredients

• 8 large eggs
• 1 cup (240ml) whole milk
• 1/2 cup (60g) shredded cheddar cheese
• 1/4 cup (30g) grated Parmesan cheese
• 1/2 cup (75g) diced red bell pepper
• 1/2 cup (75g) diced green bell pepper
• 1/4 cup (40g) finely chopped red onion
• 2 tablespoons chopped fresh parsley
• 1/2 teaspoon salt
• 1/4 teaspoon black pepper
• 1 avocado, sliced

📋 Instructions

1. 1Preheat oven — Preheat your oven to 350°F (175°C). Grease an 8×8-inch (20×20 cm) baking dish with butter or non-stick spray.
2. 2Whisk eggs — In a large bowl, whisk the eggs and milk until well combined and slightly frothy. This incorporates air for a lighter texture.
3. 3Add ingredients — Stir in the cheddar, Parmesan, bell peppers, red onion, parsley, salt, and black pepper. Mix until evenly distributed.
4. 4Pour into dish — Pour the egg mixture into the prepared baking dish and spread it evenly.
5. 5Bake the casserole — Place in the preheated oven and bake for 30-35 minutes, or until the center is set and the top is golden brown. A knife inserted into the center should come out clean.
6. 6Rest and serve — Remove from the oven and let rest for 5 minutes. Slice into squares and serve topped with fresh avocado slices.

👨‍🍳 Chef's Note: For a spicier kick, add a pinch of red pepper flakes or a dash of hot sauce to the egg mixture.

Servings: 6

Cuisine: American

Course: Brunch

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

Written by Elena Petrova

Elena writes about travel and cultural immersion, focusing on off-the-beaten-path destinations and authentic experiences. She shares practical advice for budget-conscious travelers who want to connect with local communities.