High Protein Breakfast Casserole with Eggs, Sausage & Cheese

This high protein breakfast casserole layers eggs, turkey sausage, cottage cheese, vegetables, cheddar, and hash browns in one hearty bake. It is easy to portion for breakfast or brunch, and the sausage and potatoes are cooked before baking so the eggs set evenly without leaving watery vegetables or underdone meat.

Ingredients

1 tablespoon (15 ml) olive oil, plus a little for greasing the baking dish
1 pound (454 g) ground turkey breakfast sausage, casings removed if using links
1 small yellow onion, finely diced, about 1 cup (110 g)
1 medium red bell pepper, diced, about 1 cup (150 g)
2 cups (60 g) baby spinach, roughly chopped
10 large eggs, about 500 g without shells
1 cup (225 g) cottage cheese
½ cup (120 ml) milk
½ teaspoon (1.5 g) garlic powder
¾ teaspoon (4.5 g) fine salt
½ teaspoon (1 g) ground black pepper
16 ounces (454 g) frozen shredded hash browns, thawed and patted dry
1½ cups (170 g) shredded sharp cheddar cheese, divided
2 tablespoons (8 g) chopped chives, optional, for serving

Instructions

Thaw the hash browns in the refrigerator overnight, or use the microwave according to the package directions, then blot them dry with a clean kitchen towel. Heat the oven to 375°F (190°C). Lightly grease a 9-by-13-inch (23-by-33-cm) baking dish. Drying the potatoes is useful: excess ice and water can make the finished casserole soft and slow to set.
Warm the olive oil in a large skillet over medium heat. Add the turkey sausage and break it into small crumbles with a wooden spoon. Cook for about 7–9 minutes, stirring and turning the pieces, until no pink remains and a thermometer in the thickest pieces reads 165°F (74°C), the USDA FSIS safe minimum for poultry. Transfer the cooked sausage to a plate, leaving a thin film of fat in the pan if there is any.
Add the onion and bell pepper to the same skillet and cook for 3–4 minutes, stirring, until the onion begins to soften but the pepper still holds its shape. Add the spinach and stir for about 1 minute, just until wilted. Take the pan off the heat. If the vegetables release liquid, drain it before adding them to the dish; this helps the eggs bake up tender rather than watery.
In a large bowl, whisk the eggs until the whites and yolks are blended. Whisk in the cottage cheese, milk, garlic powder, salt, and black pepper. The cottage cheese does not need to be completely smooth; its small curds soften as the casserole bakes. If you prefer a uniform custard, briefly blend the cottage cheese and milk before whisking them with the eggs.
Spread the dried hash browns across the bottom of the prepared dish. Scatter the cooked sausage and sautéed vegetables over the potatoes, distributing them into an even layer. Sprinkle about 1 cup (115 g) of the cheddar over the filling. Pour the egg mixture slowly over everything, then gently nudge the ingredients with a fork so the liquid reaches the corners without compressing the potatoes.
Top with the remaining ½ cup (55 g) cheddar. Bake uncovered for 45–50 minutes, until the edges are set and the center no longer ripples when the dish is moved. Check the center with a food thermometer: USDA FSIS guidance sets 160°F (71°C) as the safe minimum internal temperature for egg dishes. If the top is browning before the center reaches that temperature, loosely cover the dish with foil and continue baking, checking again after a few minutes.
Set the casserole on a heat-safe surface and rest it for 10 minutes before cutting. The short rest lets the custard finish settling, so portions lift out more cleanly. Sprinkle with chives if you like, cut into eight portions, and serve warm.

Tips

Dry the potatoes and vegetables. Thawed hash browns can hold a surprising amount of water, and spinach or peppers can release moisture as they cook. Pat the potatoes dry and drain any liquid from the skillet before layering. These small steps make a noticeable difference to the texture, especially in the middle of a deep casserole.
Use a thermometer rather than color alone. The top can look browned before the center is fully set, particularly if the dish is cold or the hash browns were not completely thawed. Check the center without touching the bottom of the pan, and give it a few more minutes if needed. Avoid prolonged baking after it reaches temperature, which can make the eggs firm and rubbery.
Choose sausage to suit your salt preference. Breakfast sausage varies in seasoning. If yours is strongly seasoned or salty, reduce the added salt to ½ teaspoon (3 g), then taste the cooked filling before assembling if you are unsure. For a milder flavor, use plain ground turkey and season it with a little dried sage and paprika while it cooks.
Make clean slices. Let the casserole rest for the full 10 minutes, then use a thin spatula to loosen the edges and cut with a sharp knife. For neater portions for a buffet, wipe the knife between cuts. The first piece may be less tidy than the rest, so lift it carefully and use it to create room for the next serving.

Serving Suggestions

Serve a warm square with fruit, sliced tomatoes, or a simple green salad for a meal with fresh, crisp contrast. Toast, English muffins, or warm tortillas are useful alongside if you are feeding a group with bigger appetites. For brunch, put out salsa, hot sauce, plain yogurt, and extra chopped chives so people can add their preferred toppings without changing the casserole itself.

This bake is filling enough to serve as the main dish, so a complicated side is not necessary. If you are serving it with other hot dishes, cut it into smaller pieces and keep it covered loosely with foil while it waits. Avoid leaving egg dishes at room temperature for an extended brunch; refrigerate leftovers within two hours, or sooner if the room is especially warm.

Variations

Use pork sausage: Replace the turkey sausage with 1 pound (454 g) ground pork breakfast sausage. Cook ground pork to 160°F (71°C), the USDA FSIS safe minimum for ground meat, before assembling. Pork sausage is often fattier and more strongly seasoned than turkey, so drain excess fat and consider reducing the added salt.

Make it meatless: Leave out the sausage and add 8 ounces (225 g) sliced mushrooms, cooked until their released liquid evaporates. You can also use a vegetarian breakfast crumble; cook it according to its package directions. The casserole will have a different savory flavor, so season the vegetables with a pinch of smoked paprika or dried sage if desired.

Change the vegetables: Replace the bell pepper with chopped broccoli florets, mushrooms, or zucchini. Cook firm vegetables until just tender before layering; cook watery vegetables until their moisture has evaporated. Broccoli should be cut into small pieces so it softens during the bake. Keep the total amount of vegetables close to the recipe quantity to avoid crowding the egg mixture.

Swap the cheese or potatoes: Monterey Jack or a mild cheddar can replace sharp cheddar in the same quantity. For a different potato texture, use thawed diced hash browns instead of shredded ones. Cottage cheese may be replaced with the same amount of ricotta, though ricotta makes the egg mixture thicker and less tangy. Do not replace it with a much larger quantity of milk, since extra liquid can prevent the center from setting on schedule.

Storage and Reheating

Let leftovers cool briefly, then refrigerate them in a covered container within two hours of baking. Keep the casserole refrigerated for 3–4 days. For convenient breakfasts, cut it into portions before storing; individual pieces are easier to reheat evenly than one large slab. Keep toppings such as salsa or fresh herbs separate and add them just before serving.

To reheat one portion, cover it loosely and microwave in short bursts, turning or repositioning it as needed, until hot throughout. For several portions, place them in an oven-safe dish, cover with foil, and warm at 325°F (165°C). Leftovers should reach 165°F (74°C) when checked with a food thermometer, in line with USDA FSIS reheating guidance. The exact time depends on portion size and whether it is reheated from cold or frozen, so temperature is more reliable than a fixed minute count.

To freeze, cool the casserole, wrap individual portions well, and freeze for up to 2–3 months for best quality. Thaw overnight in the refrigerator before reheating, or heat from frozen at a moderate oven temperature until the center reaches 165°F (74°C). The potatoes may soften slightly after freezing, but the portions remain convenient. Do not leave cooked casserole at room temperature for more than two hours while cooling or serving.

Frequently Asked Questions

Can I assemble the casserole the night before?

Yes. Cook the sausage and vegetables, cool them promptly, and assemble the casserole in a covered baking dish. Refrigerate it overnight and bake the next morning. Since a chilled dish starts colder than a freshly assembled one, it may need additional oven time; check that the center reaches 160°F (71°C) rather than relying only on the listed range. Do not put a cold glass dish straight into a hot oven unless its manufacturer says it is safe to do so.

Do I have to thaw the hash browns first?

Thawing and drying them gives the most predictable result because frozen potatoes release moisture and can cool the egg mixture. If you need to use them frozen, spread them in the dish and expect a longer bake, checking the center temperature carefully. Avoid adding a thick frozen block of potatoes, which can make the casserole cook unevenly while the edges overbake.

Can I use egg whites instead of whole eggs?

You can substitute liquid egg whites, but they do not have the same richness or texture as whole eggs. Use the conversion on the carton for the equivalent of 10 large eggs, and check the casserole with a thermometer because the setting time may differ. If using a carton product, follow its storage and handling instructions after opening.

How can I tell whether the casserole is done without overbaking it?

Look for set edges and a center that does not visibly slosh, then check the middle with an instant-read thermometer. Egg dishes need to reach 160°F (71°C) for the USDA FSIS safe minimum. If the center is below that point, continue baking in short intervals and check again. Resting the casserole after baking helps it settle, but the rest does not replace reaching the required temperature in the oven.

Can I make this without cottage cheese?

Yes. Use 1 cup (225 g) ricotta for a thicker, mild result, or plain Greek-style yogurt for a tangier one. Stir either substitute into the eggs and milk before pouring. Cottage cheese contributes both moisture and a slightly curdy texture, so the finished casserole will not be identical with another dairy ingredient. Avoid adding extra milk to compensate; a thinner mixture can take longer to set.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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