Protein-Packed Breakfast Casserole

This Breakfast Casserole is a hearty, protein-packed morning meal perfect for family gatherings or a make-ahead weekday breakfast.

Combining eggs, savory pork sausage, and cheddar cheese, it delivers a satisfying balance of protein and healthy fats, while fresh bell peppers and green onions provide fiber, vitamins, and natural sweetness.

Low in carbohydrates and high in protein, this casserole supports sustained energy and keeps you full for hours.

Its simplicity and adaptability make it ideal for everyday cooking—just prep, assemble, and bake.

You can customize it with your favorite vegetables or cheeses, and it reheats beautifully for quick breakfasts throughout the week.

Whether for a festive holiday brunch or a practical weekday meal, this breakfast casserole is flavorful, comforting, and convenient, making it a versatile staple for busy households.

Must-Have Tools for Perfect Results

9×13 Glass Baking Dish

Provides even heat distribution, ensuring the casserole cooks uniformly with a golden-brown top, and is perfect for serving directly from the dish.

Large Mixing Bowl

Combines eggs, sour cream, milk, cheese, and seasonings efficiently, allowing smooth incorporation of ingredients without mess.

Electric Mixer

Quickly blends egg and dairy mixture to a consistent, airy texture, preventing overmixing while saving time.

Skillet

Essential for browning sausage and sautéing vegetables evenly, releasing flavor while removing excess grease for a healthier casserole.

Meat Chopper or Wooden Spoon

Breaks sausage into small, uniform pieces for even distribution throughout the casserole, ensuring every bite has a perfect balance of meat and veggies.

Savory Breakfast Casserole

Jessica T. Brown

A savory, protein-rich breakfast casserole with eggs, sausage, cheddar, and fresh bell peppers, perfect for make-ahead mornings, family brunches, or weekday breakfasts, high in protein and low in carbs.

Print Recipe Pin Recipe

Prep Time 10 minutes mins

Cook Time 55 minutes mins

Total Time 1 hour hr 5 minutes mins

Course Breakfast, Brunch

Cuisine American

Servings 12

Equipment

• 1 9×13 Glass Baking Dish
• 1 Large mixing bowl
• 1 Electric Mixer
• 1 Skillet
• 1 Meat Chopper or Wooden Spoon

Ingredients

  

• 2 pounds pork sausage
• 12 eggs
• 1 cup sour cream light or regular
• 1/4 cup milk
• 1 teaspoon kosher salt
• 1/2 teaspoon ground black pepper
• 4 green onions chopped
• 1/2 green bell pepper diced
• 1/2 red bell pepper diced
• 2 cups shredded cheddar cheese

Instructions

 

• Preheat Oven: Set your oven to 350°F (175°C) and lightly grease a 9×13-inch glass baking dish with cooking spray or butter.

  Proper preheating ensures even cooking and a golden, firm top.
• Mix Eggs and Dairy: In a large mixing bowl, combine all 12 eggs, 1 cup sour cream, 1/4 cup milk, salt, and pepper.

  Use an electric mixer on low speed to blend until smooth and slightly airy, avoiding overmixing.
• Cook the Sausage: Heat a large skillet over medium heat and add 2 pounds of pork sausage. Break the sausage into small pieces using a wooden spoon or meat chopper and cook until browned. Drain excess grease for a healthier casserole.
• Sauté Vegetables: In the same skillet, add diced green and red bell peppers along with chopped green onions.

  Sauté for 2–3 minutes until softened, enhancing flavor and preserving a slight crunch.
• Combine Ingredients: Add the cooked sausage and sautéed vegetables to the egg mixture.

  Stir gently to evenly distribute ingredients, ensuring every bite has a balanced mix of protein, cheese, and vegetables.
• Add Cheese and Pour: Fold in 2 cups of shredded cheddar cheese, then pour the complete mixture into the prepared 9×13 baking dish.

  Spread evenly to ensure uniform cooking throughout the casserole.
• Bake to Perfection: Bake in the preheated oven for 35–50 minutes.

  The casserole is done when the edges are set and the center is just slightly jiggly.

  Allow to rest for 5–10 minutes before serving to make slicing easier and maintain structure.

Notes

• Make Ahead Option: This casserole can be assembled the night before and stored in the fridge, making mornings stress-free. Bake directly from chilled.
• Customize Ingredients: Swap pork sausage for turkey sausage, chicken sausage, or a plant-based alternative. Add mushrooms, spinach, or tomatoes for extra veggies.
• Cheese Variations: Cheddar works perfectly, but Swiss, mozzarella, or pepper jack can be used for different flavor profiles.
• Cooking Time Adjustment: Oven temperatures vary; check at 35 minutes and bake longer if the center is still jiggly.
• Portion Control: This recipe serves 12; slice into squares or rectangles for easy serving and meal prep.

Chef’s Secrets For Perfect Casseroles

The secret to a perfectly textured breakfast casserole is layering flavor and controlling moisture.

Browning sausage first releases rich, savory oils while reducing excess grease, preventing a soggy base.

Lightly sautéing bell peppers and onions enhances sweetness and keeps vegetables tender-crisp.

Mixing eggs, sour cream, and milk gently with an electric mixer creates a creamy, slightly airy custard.

Avoid overmixing to retain structure. Adding cheese at the end ensures melty pockets throughout the casserole.

Finally, letting the casserole rest after baking allows it to firm up, making slicing clean and effortless.

Small adjustments, like seasoning vegetables or choosing bold cheeses, elevate this simple dish into a crowd-pleasing breakfast centerpiece.

Serving Suggestions For Brunch Gatherings

Serve this casserole warm, straight from the baking dish, paired with fresh fruit, mixed greens, or a light yogurt parfait.

Top with extra shredded cheese, sliced avocado, or a dollop of sour cream for added richness.

For festive occasions, garnish with fresh herbs like parsley or chives.

Pair with freshly brewed coffee, tea, or orange juice to complete a hearty, balanced breakfast or brunch spread.

The casserole also works perfectly for potlucks or holiday mornings where multiple dishes are shared.

Storage Tips For Freshness And Flavor

Store leftovers in an airtight container in the refrigerator for up to 3–4 days.

Reheat individual portions in the microwave for 45–60 seconds or in a preheated oven at 350°F for 10–15 minutes to maintain texture.

For longer storage, freeze the baked casserole in portioned squares for up to 2 months; thaw overnight in the fridge before reheating.

Avoid leaving the casserole at room temperature for extended periods to preserve safety and flavor.

Using glass or ceramic bakeware helps even reheating without drying out the dish.

Frequently Asked Questions Answered

1. Can I make this casserole vegetarian?

Yes! Replace sausage with plant-based sausage or sautéed vegetables like mushrooms and zucchini for a vegetarian-friendly version.

2. Can I prepare this the night before?

Absolutely. Assemble the casserole in the baking dish, cover tightly, and refrigerate overnight. Bake straight from the fridge in the morning.

3. What cheese works best?

Cheddar is classic, but Swiss, mozzarella, or pepper jack can be used to create different flavor profiles.

4. How do I avoid a soggy casserole?

Brown the sausage thoroughly and drain excess grease. Sauté vegetables lightly to remove excess moisture before adding them to the egg mixture.

5. Can I freeze leftover casserole?

Yes, slice into portions, wrap tightly, and freeze up to 2 months. Thaw in the refrigerator overnight before reheating.