This hearty sausage breakfast casserole combines savory sausage, tender potatoes, bell peppers, and onions baked into a cheesy egg custard. Perfect for brunch or an easy make-ahead meal for busy mornings!
Recipe Science
- Browning the sausage deepens the flavor through the Maillard reaction while rendering excess fat, preventing a greasy casserole.
- Sautéing the potatoes and veggies enhances the flavor while reducing excess moisture, preventing a soggy casserole.
- Cornstarch prevents curdling by absorbing moisture for a smooth, stable custard. As it bakes, it thickens for a firm yet tender texture.
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Why It Works
Sausage breakfast casserole is about getting the right texture and moisture balance. Cornstarch is the secret ingredient that helps the eggs and half-and-half blend into a smooth, creamy custard without getting watery or rubbery. Sautéing the sausage, potatoes, and veggies first locks in flavor and keeps the casserole from becoming soggy. The result? A cheesy, hearty dish with perfectly set eggs in every bite.
This recipe is a go-to for busy mornings, holiday brunches, or easy meal prep. You can assemble it ahead of time, pop it in the oven when you’re ready, and have a warm, satisfying breakfast all week. This casserole is perfect for Easter brunch, Christmas morning, or just a regular Monday!
Ingredients You’ll Need
- Sausage: I use fresh ground pork sausage, which adds a rich, savory flavor and protein. Browning the sausage first enhances its taste and prevents excess grease from making the casserole too oily.
- Oil: Olive oil is used for sautéing the potatoes and vegetables, helping to develop a golden crust and prevent sticking.
- Potatoes: Yukon gold potatoes are creamy and buttery, hold their shape well, and add heartiness to the casserole. Cooking them beforehand ensures that they are tender.
- Onions: Diced red onion adds a mild sweetness and depth of flavor. Sautéing softens the onions and enhances their natural sugars.
- Garlic: Mince garlic boosts the dish’s overall savoriness with its aromatic, slightly pungent flavor. Cooking it briefly ensures it doesn’t become bitter.
- Bell Peppers: Diced bell peppers add a pop of color and mild sweetness. I like adding a mix of green and red bell peppers for various flavors.
- Green Onions: Provides a fresh, mild onion flavor and a bright contrast to the rich ingredients.
- Seasoning: Salt is used in the sautéing process, while the rest is mixed into the egg custard for an even seasoning. Black pepper adds a delicate, spicy taste.
- Cheese: Sharp cheddar cheese melts into the egg custard, adding a creamy, tangy, slightly salty flavor.
- Cornstarch: The key to a smooth, creamy custard. It binds the eggs and half-and-half, preventing the mixture from separating or turning watery while baking.
- Dairy: Half-and-half contains about 12% milkfat, creating a rich custard texture without being too heavy.
- Eggs: The star of the custard, eggs provide structure and create a light, fluffy texture that holds all the ingredients together.
See the recipe card below for all ingredients and measurements (US and metric).
Ingredient Substitutions
This sausage breakfast casserole is easy to customize! Try these delicious options:
- Sausage Options: Instead of using traditional pork sausage, you can try using spicy Italian sausage, chorizo, turkey or chicken sausage, breakfast sausage links, or vegetarian sausage alternatives.
- Add More Vegetables: Add sauteed mushrooms, sun-dried tomatoes, broccoli, spinach, kale, tomatoes, russet potatoes, hashbrowns, or sweet potatoes. Add a sweet touch with caramelized onions.
- Seasonings: Add garlic powder, onion powder, dry mustard, paprika, cayenne pepper, thyme, rosemary, or dried Italian seasoning.
- Cheese Swaps: Try using different types of cheese, such as smoked gouda, swiss, monetary jack, pepper jack, parmesan, mozzarella, feta, or even goat cheese.
- Half-and Half Substitute: Combine equal parts of whole milk and heavy cream. Alternatively, mix milk with sour cream or plain Greek yogurt.
How to Make Sausage Breakfast Casserole
Step 1: Heat the Oven
Preheating to 350ºF (177ºC) allows the egg custard to set smoothly without curdling. This helps the cornstarch-thickened custard gel properly, preventing a watery or rubbery texture. Placing the rack in the center ensures balanced heat distribution, preventing overcooking on the top or bottom.
Pro Tip: Greasing the baking dish with olive oil prevents food from sticking and ensures even baking, making it easy to slice and serve.
Step 2: Saute the Sausage
Cooking the sausage over medium heat in a large skillet allows it to brown evenly while developing rich, savory flavors through the Maillard reaction. Make sure to break the sausage into smaller chunks with a metal or wooden spoon while it is still raw. As the proteins cook, they bind tightly, making separation harder. Alternatively, you can shape the sausage into round balls before adding it to the pan.
Tips for Perfect Execution: Spreading the cooked sausage evenly in the baking dish ensures every bite gets a balanced mix of meat, eggs, and cheese.
Step 3: Saute the Potatoes
Sautéing jump-starts starch gelatinization, softening the potatoes while creating a lightly crisp surface for better texture. Olive oil ensures even browning and adds flavor, while occasional stirring prevents sticking and even crisping.
Step 4: Saute the Mix-ins
Sautéing onions and garlic enhances their sweetness and mellows their pungency. Cook the bell peppers to retain some crunch. Seasoning early deepens the flavor, and adding green onions off-heat keeps them fresh.
Spread the vegetables and sausage evenly in the pan and layer cheddar cheese on top to create a rich, melty base.
Step 5: Add the Egg Base
Whisking the cornstarch, salt, half-and-half, and eggs thoroughly ensures an even distribution of fat and proteins, creating a uniform custard. Pouring it evenly over the mix-ins helps everything bind together, while topping it with cheese adds a golden crust after baking.
Ingredient Chemistry: Cornstarch stabilizes the custard by binding excess moisture, preventing the eggs from curdling, and ensuring a smooth, creamy texture. As the casserole bakes, the starch molecules absorb liquid, swell, and gelatinize, thickening the mixture for a firm yet tender bite.
Step 6: Bake the Casserole
Baking at a moderate temperature for about 40 minutes allows the custard to set gradually. Rotate the pan to avoid undercooked or overly browned spots. Cool for 10 minutes and let the custard firm up, making slicing easier while preventing excess moisture loss.
Expert Tip: The casserole is fully set when it reaches an internal temperature of 180–190ºF (82–88ºC). This is the ideal range for egg coagulation, where proteins form a stable structure without becoming rubbery.
Frequently Asked Questions
You can assemble the casserole up to one day in advance, cover it, and store it in the refrigerator. Since the ingredients and pan are cold, it will take longer to bake.
You can reheat the whole casserole in a 300°F (149°C) oven until it is warmed in the center. Cover the surface with aluminum foil if it browns too quickly. Alternatively, store leftovers in an airtight container for up to 5 days in the refrigerator, and reheat individual slices in the microwave for about 1 minute or until hot.
Yes! You can freeze the breakfast casserole for later. Bake it first, let it cool completely, then wrap it tightly in plastic wrap and foil. Freeze for up to 3 months. To reheat, thaw it overnight in the fridge and warm it in a 300°F (149°C) oven until heated.
Yes, you’ll need 4 cups of frozen diced or shredded hashbrowns. Defrost in the microwave before adding. Saute for about 5 to 7 minutes.
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Sausage Breakfast Casserole
Ingredients
- 1 pound ground pork sausage
- 2 tablespoons olive oil
- 1 ½ pounds Yukon gold potatoes, ¼" dice
- 1 cup red onion, ⅛" dice
- ½ cup diced red bell pepper, ⅛" dice
- ½ cup diced green bell pepper, ⅛" dice
- 1 tablespoon minced garlic
- 1 ½ teaspoons kosher salt, divided
- ¼ teaspoon black pepper
- ¼ cup sliced green onions
- 1 ¾ cup grated sharp cheddar cheese, 6 ounces
- ¼ cup cornstarch
- 2 ½ cups half-and-half
- 8 large eggs
Instructions
- Heat the Oven – Set the oven rack to the center position. Preheat to 350ºF (177ºC). Grease a 9×13-inch baking dish with olive oil on the bottom and sides.
- Saute the Sausage – Heat a large pan or cast iron skillet over medium heat. Once hot, add in the sausage. Use a spoon to break it into smaller chunks. Saute until fully cooked and browned, about 3 to 4 minutes. Evenly spread into the baking dish. Drain off most of the fat from the pan.
- Saute the Potatoes – Heat the pan over medium-high heat. Add 2 tablespoons of olive oil. Once hot, add the potatoes. Saute until tender, occasionally stirring, about 8 to 10 minutes.
- Saute the Mix-ins – Turn the heat down to medium. Add the onions and garlic and saute for 1 minute. Add the bell peppers and saute for 2 minutes. Turn off the heat and stir in ½ teaspoon salt, black pepper, and green onions.Transfer the mixture to the greased baking dish, mix it with the sausage, and spread it into an even layer. Evenly sprinkle half of the cheddar cheese on top.
- Add the Egg Base – In a large bowl, whisk together the cornstarch and 1 teaspoon salt. Add the half-and-half and eggs and whisk until thoroughly combined. Pour the egg mixture into the baking dish. Evenly sprinkle the remaining cheese on top.
- Bake the Casserole – Bake for 20 minutes. Rotate the pan and continue baking until the center sets and a toothpick inserted comes out clean, about 20 minutes. The internal temperature should be 180 to 190ºF (82 to 88ºC). Cool for 10 minutes before slicing and serving.
Notes
- Make Ahead: Assemble the casserole up to 1 day in advance, cover, and refrigerate. Baking time will be longer since the pan and ingredients will be cold.
- Reheating Baked Casserole: Warm the whole casserole in a 300°F (149°C) oven until heated through. Cover with foil if it browns too quickly.
- Freezing: Bake first, let cool completely, then wrap tightly in plastic wrap and foil. Freeze for up to 3 months. Thaw it overnight in the fridge and reheat it in a 300°F (149°C) oven until warm.
- Storing: For leftovers, store in an airtight container for up to 5 days and microwave individual slices for about 1 minute.
Nutrition Facts
Percent Daily Values are based on a 2000-calorie diet. All nutritional information is based on estimated third-party calculations. Each recipe and nutritional value will vary depending on the brands you use, measuring methods, and portion sizes per household.
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