This easy high protein breakfast casserole is simple, healthy, delicious, and loaded with 28 grams of protein per serving! It can be made the night before and left to sit overnight for the perfect balanced breakfast or brunch the next day. A family favorite that is great for meal prep or serving company during the holidays or any time of year!
Table of Contents
Easy High Protein Egg Casserole
When you have a hungry tribe to feed in the morning, this high protein breakfast casserole is an easy and effortless option.
Made with just a few simple ingredients, it can be made the night before and baked in the oven in the morning for a delicious feast perfect for a crowd. It also works well for weekly meal prep for those crazy busy mornings!
For more make ahead breakfasts, be sure to check out my Egg White Breakfast Casserole, Blueberry French Toast Casserole, and High Protein Breakfast Burritos.
Why We Love This Healthy Breakfast Casserole Recipe
- With the eggs, sausage, cheese and milk, this easy breakfast casserole is a great source of protein which can leave you feeling full and satisfied, so you’re less likely to arrive at the dinner table feeling ravenous and wanting to eat everything in sight.
- Made with lean sausage, eggs, and bell peppers, this high-protein breakfast casserole is a great option for breakfast or brunch, and it takes minimal time to prepare.
- This hearty casserole is so satisfying and flavorful that you can even serve it as a quick lunch.
- The whole-grain bread and veggies also offer a nice dose of fiber to help keep that digestive system in gear.
Ingredient Notes
Eggs: The eggs form the base of the recipe and add lots of high-quality protein. Use brown or white; there is no nutritional difference.
Sausages: Use lean breakfast sausages or turkey sausages to reduce saturated fat content. If vegetarian, you can also use a meat-free or plant-based sausage, or leave the sausage out all together. You can also use ground sausage or remove the sausage from the casing if you prefer the sausage to be more evenly distributed throughout the casserole.
Bread: You can use whole grain bread or sub in gluten-free if there are any intolerances. French bread or sourdough bread also work well.
Milk: We use regular 1% milk when making this casserole, but you can sub in your preferred milk or milk alternative to make it dairy-free. The higher the fat percentage, the richer it will be.
Bell peppers: Are a great way to add some nutrient-rich vegetables into this dish. I used green and red bell pepper to add a nice pop of color and to make it more festive, but feel free to use other colors. You can also sub in other vegetables like spinach, kale, asparagus or broccoli, if desired.
Cheese: I used an old cheddar cheese for extra flavor. Feel free to use your preferred cheese or sub in a plant-based cheese to make it dairy-free. Other cheeses that would work well include Swiss, pepper jack cheese, gouda, mozzarella, or feta cheese.
Step-by-Step Instructions
Step 1: Cook Sausage & Peppers
- In a frying pan over medium heat, brown sausages, about 6-7 minutes. Remove the sausages from the pan and pat down well with paper towel to get rid of excess grease.
- In the same pan, cook the peppers for about 5-6 minutes or until softened.
Step 2: Prepare Egg Mixture
- In a medium-sized bowl, beat eggs with milk, salt, pepper and dry mustard.
Step 3: Assemble Casserole in Baking Dish
- Spray a 9 x13 inch casserole dish with cooking spray or grease using your preferred method.
- Distribute sausages evenly across the bottom of the dish. Next, evenly spread the cubed bread and sliced peppers on top of the sausages. Pour the egg mixture over the sausage, bread and peppers. Top with shredded cheese.
- Allow casserole mixture to sit in the fridge for at least 2 hours or overnight.
- When ready to bake, preheat oven to 350 degrees F. Bake for 60-80 minutes or until egg is set when you cut into it and casserole is slightly browned and puffy on the top. Allow the casserole to cool for at least 15 minutes to allow it to set.
Expert Tips
- Use lean sausages to eliminate excess saturated fat. An increasing number of grocery stores are starting to offer this now. Or you could even sub in turkey breakfast sausages as well.
- Be sure to pat down the sausages well with paper towel after cooking to eliminate any excess grease.
- To make this vegetarian, leave out the sausage and add an extra cup or so of vegetables.
- You may wish to toast the bread or use bread that is a couple of days old so that it has a chance to dry out. This will make the bread a little more crusty and will help it better absorb the egg mixture.
- If you choose to add more vegetables, make sure that you cook them first to allow some of the moisture to evaporate from them before adding them to the baking dish to prevent the casserole from becoming soggy.
- The egg casserole is done when the egg is no longer runny and it’s puffy and golden on top.
- Allow the casserole to sit for at least 15 minutes to allow it to set before cutting.
Storage Guidelines
How to Store: If you have leftovers, you can store them covered in the fridge for up to four days. I like to portion out the leftovers in an airtight container and reheat a single slice at a time.
How to Freeze: Prepare the recipe through step 5, then cover the casserole with plastic wrap, then a piece of aluminum foil. Freeze for up to 3 months.
When ready to cook, allow to thaw overnight in the refrigerator. Bring to room temperature, then continue with step 6.
How to Reheat: Microwave individual servings for 1-2 minutes or until heated all the way through. For larger portions, cover the baking dish with foil and bake at 350 F for 20-30 minutes.
Recipe FAQs
Not necessarily. Although it can be an overnight breakfast casserole, if pressed for time, you don’t have to let it sit overnight. I would say that letting it sit for at least 2 hours before putting it in the oven would be sufficient. That’s what I did last time I made it and it turned out just as good as when I let it sit overnight.
Of course! This is a really versatile recipe and you can easily add in whatever vegetables you have on hand. Other vegetables that would work well include mushrooms, spinach, kale, asparagus or broccoli.
Just be sure to cook them first if they tend to be more watery to allow some of that extra moisture to evaporate before combining with the rest of the casserole ingredients.
More and more people are learning just how helpful it is to load up on protein early in the day! Not only does protein help with energy, feelings of fullness, and muscle recovery, but it can also help prevent snacky cravings all day.
It’s a good rule of thumb to consume 20-30g of protein at breakfast. Since this healthy egg bake has 28g of protein per serving, it’s the perfect protein-packed breakfast for people trying to maximize their protein intake!
Serving Suggestions
Although this casserole is pretty filling on its own, you could always serve it along with some muffins (these Almond Flour Apple Muffins are delicious!), and a nice fruit salad if you’re serving it for breakfast (try this Christmas Fruit Salad or Christmas Fruit Wreath).
It also pairs well with roasted sweet potatoes or this Spinach Orange Salad or Christmas Wreath Salad if serving it as more of a lunch or dinner option. Either way, you can’t go wrong!
Recipe Variations
- Add different vegetables: You can really get creative with veggies here! Try adding some greens, like kale or spinach, green onions, chopped broccoli, diced white onion, mushrooms, asparagus, sliced red onion, etc. Just be sure to cook them first if they tend to be more watery to allow some of that extra moisture to evaporate before combining with the rest of the casserole ingredients.
- Add extra protein: To increase the protein and reduce the fat, replace some of the whole eggs with egg whites. You can also stir some cottage cheese into the egg mixture before baking, which will melt and make it extra creamy and cheesy.
- Try a different meat: Instead of sausage, add regular or turkey bacon.
- Play with garnishes: I love serving this egg breakfast casserole with a little salsa (extra veggies!) or an avocado slice for extra creaminess.
More Recipes You’ll Love
- Crustless Asparagus Quiche
- Scrambled Eggs without Milk
- Sausage Tray Bake
- Turkey Sausage Egg Muffins
- Spinach Zucchini Frittata
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High Protein Breakfast Casserole
Ingredients
- 1 lb lean breakfast sausages can also sub in turkey breakfast sausages
- 1/2 medium red pepper, sliced or diced
- 1/2 medium green pepper, sliced or diced
- 6 large eggs
- 2 cups milk
- 1 teaspoon dry mustard
- 1/2 teaspoon each salt and pepper
- 2 cups cubed whole-wheat or sourdough bread (can also sub in gluten-free bread if necessary)
- 1 cup shredded cheddar cheese
Instructions
- In a frying pan over medium heat, remove casing from the sausages and cook while breaking up with a wooden spoon until browned, about 6-7 minutes. Remove the ground sausage from the pan and pat down well with some paper towel to get rid of excess grease.
- In the same pan, cook the peppers for about 5-6 minutes or until softened. Pat with paper towel to absorb extra moisture.
- In a medium-sized bowl, beat eggs with milk, dry mustard, salt, and pepper.
- Spray a 9 x 13 inch casserole dish with cooking spray.
- Distribute cooked sausage meat and cubed bread evenly across the bottom of the dish. Next, evenly spread the sliced peppers on top of the sausage and bread, tucking some under the bread. Pour the egg mixture over the sausage, bread and peppers. Top with shredded cheese.
- Allow casserole mixture to sit in the fridge for at least 2 hours or overnight.
- When ready to bake, preheat oven to 350 degrees F. Bake for 60-80 minutes or until egg is set when you cut into it and casserole is slightly browned on the top. Allow casserole to cool for at least 10 minutes to allow it to set.
Notes
- Use lean sausages to eliminate excess saturated fat. Or you could even sub in turkey breakfast sausages as well.
- Be sure to pat down the sausages well with paper towel after cooking to eliminate any excess grease.
- You may wish to toast the bread or use bread that is a couple of days old so that it has a chance to dry out. This will make the bread a little more crusty and will help it better absorb the egg mixture.
- If you choose to add more vegetables, make sure that you cook them first to allow some of the moisture to evaporate from them before adding them to the baking dish to prevent the casserole from becoming soggy.
- The egg casserole is done when the egg is no longer runny and it’s puffy and golden on top.
- Allow the casserole to sit for at least 15 minutes to allow it to set before cutting.
- To freeze: Prepare the recipe through step 5, then cover the casserole with plastic wrap, then a piece of aluminum foil. Freeze for up to 3 months. When ready to cook, allow to thaw overnight in the refrigerator. Bring to room temperature, then continue with step 6.
Nutrition
This recipe was originally posted in December 2018 and was updated in October 2024 to include more helpful tips and photos.
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