High-Protein Breakfast Casserole You Can Bake Once and Eat All Week

Some weeks call for a breakfast you can bake once and forget about — high-protein breakfast casserole is exactly that. Whisk, pour, bake — and you’ve got 8 squares with 27 grams of protein each, ready to reheat for busy mornings without touching a pan again. For more make-ahead mornings like this one, check out our full High-Protein Breakfast Meal Prep roundup.

Why You’ll Love This Recipe

• High-protein breakfast casserole with 27g of protein per serving — more than two fast-food breakfast sandwiches combined.
• One dish, one bake — no standing at the stove flipping anything.
• Feeds a crowd or a whole week — this high-protein breakfast casserole yields 8 squares from a single 9×13-inch dish.
• Endlessly customizable — swap the veggies and it never gets boring.

Ingredients Overview

High-protein breakfast casserole gets its protein boost from a mix of whole eggs, egg whites, and cottage cheese, whisked together so the finished bake stays soft instead of rubbery. Bell peppers and spinach round out the dish with color and nutrients. According to USDA MyPlate, adding vegetables like peppers and leafy greens to a protein-forward meal is an easy way to round out your plate without extra prep steps.

Turkey sausage adds savory flavor without the extra fat of pork sausage, and shredded cheddar melts through the top for a golden finish. Every ingredient here is easy to find at a regular grocery store, so there’s no special shopping trip required.

Step-by-Step Instructions

Follow these simple steps to make your High-Protein Breakfast Casserole from start to finish:

1. Preheat your oven to 350°F and grease a 9×13-inch baking dish with cooking spray.
2. In a large bowl, whisk together the eggs, egg whites, cottage cheese, garlic powder, salt, and pepper.
3. Stir in the cooked turkey sausage, bell peppers, spinach, and half the shredded cheddar.
4. Pour the mixture into the prepared baking dish and top with the remaining cheddar.
5. Bake for 35-40 minutes, until the center is set and the top is lightly golden, then let cool for 10 minutes before slicing.

💡 Pro Tip: Let your high-protein breakfast casserole cool completely before slicing and storing, so the squares hold together instead of falling apart.

Meal Prep & Storage Tips

High-protein breakfast casserole is one of the most freezer-friendly recipes in this silo, since it slices into neat, reheatable squares. Sealed in an airtight container, it keeps in the fridge for up to 5 days, or in the freezer for up to 2 months. Reheat a square in the microwave for 60-90 seconds from the fridge, or closer to 2 minutes from frozen.

If you’re prepping for the whole week, slice the cooled casserole into 8 squares and store them in individual containers so grabbing breakfast takes zero thinking on a rushed morning. Avoid reheating in the toaster oven, which can dry out the edges.

Variations & Substitutions

Swap the bell peppers and spinach for broccoli and mushrooms, or use pepper jack instead of cheddar for a spicier finish. Dairy-sensitive? Cottage cheese can be swapped for an equal amount of Greek yogurt without changing the texture much. For a vegetarian version of this high-protein breakfast casserole, skip the turkey sausage and add an extra cup of vegetables in its place.

FAQ

Can I double this High-Protein Breakfast Casserole recipe? Yes — use two baking dishes and rotate them halfway through baking for even cooking. It’s an easy way to stock the freezer for two weeks instead of one.

Why use both whole eggs and egg whites? Egg whites boost the protein count without adding extra fat, while whole eggs keep the texture rich and the flavor balanced. According to USDA MyPlate, pairing eggs with vegetables is a simple way to build a more balanced protein-forward breakfast.

Can I assemble this the night before? Yes — whisk everything together, pour it into the baking dish, cover, and refrigerate overnight. Bake straight from the fridge in the morning, adding a few extra minutes to the bake time.

Do I need to thaw a frozen square before reheating? No, you can microwave a high-protein breakfast casserole square straight from frozen — just add an extra minute or so to the reheating time compared to a fridge-stored one.

Can I use a different meat? Yes — cooked and crumbled chicken sausage or lean ground turkey both work well in place of turkey sausage, with the same protein-forward result.

Ready to Meal Prep?

High-protein breakfast casserole turns one Sunday bake into a full week of grab-and-go mornings, with zero extra cooking in between. Craving more high-protein recipes? Subscribe to our newsletter for weekly meal prep inspiration! 📩

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• High-Protein Egg Bites
• High-Protein Breakfast Burrito
• High-Protein Egg Muffins with Cottage Cheese