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This Whole30 breakfast casserole with eggs and sausage is loaded with savory sausage, fluffy eggs, and perfectly seasoned vegetables—all baked together into one satisfying, make-ahead meal. It’s amazing for busy mornings, meal prep, or feeding a ravenous family, and it reheats beautifully throughout the week. Plus, it’s naturally paleo, keto-friendly, and dairy-free!

Slice of Whole30 breakfast bake with sausage, eggs, spinach, and bell peppers on a cream plate with a fork

See recipe card below for full list of measurements, ingredients, and instructions.

Any time we’re on a Whole30, I spend a couple of hours on Sunday afternoon making dishes for the week. This usually looks like a batch of Whole30 garlic mayonnaise, Whole30 chicken salad, and Whole30 ranch dressing. But one Sunday, I was struck by the strangest, strongest urge to make a sausage and veggie bake, filled with chopped spinach, fresh tomatoes, sautéed mushrooms, and fresh herbs.

And you know what? I never tired of eating this breakfast casserole with eggs and sausage that week, not once! No, I fell in love with the creamy egg bake, the rich sausage, the fresh veggies, the flavorful herbs. With loads of veggies and plenty of protein, this Whole30 breakfast casserole might just be Whole30-perfect!

Why This Recipe is So Good

  • Bake this once on Sunday and you’ve got protein-packed breakfasts ready to grab all week long. Just reheat a slice in the microwave and you’re out the door with a satisfying, compliant breakfast in hand.
  • It’s so darn versatile! Use whatever vegetables you have on hand, swap the sausage for ground turkey or bacon, or add your favorite Whole30-approved seasonings. This recipe is incredibly forgiving and adapts to what’s in your fridge.
  • The combination of seasoned sausage, perfectly cooked eggs, and tender veggies creates a hearty, filling breakfast that’ll keep everyone satisfied for hours—no one will guess it’s Whole30!
  • If you can brown sausage and whisk eggs, you can make this breakfast bake. It’s straightforward, beginner-friendly, and comes together in about 10 minutes of active prep time. Amazing, right?!

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What You Need to Know Before You Start

  • Taking just a few extra minutes to cook down the peppers and onions removes excess moisture and concentrates their flavor. If you add raw veggies directly to the egg mixture, you’ll end up with a watery, soggy casserole—trust me on this one.
  • If you pour whisked eggs directly over piping-hot sausage, you risk scrambling them prematurely, which creates an uneven texture. Give everything about 5 minutes to cool down, and you’ll get that smooth, custard-like consistency we want!
  • Make sure you squeeze the water out of your thawed spinach; otherwise, you’ll end up with a watery mess! If you do forget, simply sauté the vegetable mixture for a longer time or until the water has evaporated.
  • Use a well-seasoned cast iron skillet if you have one (it’s forgiven if you don’t, of course!). The sausage fat creates natural non-stick properties, and cast iron distributes heat evenly for perfect browning on the bottom and edges. No cast iron? A well-greased 9×13 baking dish works beautifully, too.

Recipe Variations

Switch Up the Protein: Bacon lovers, this one’s for you—swap the sausage for crispy, crumbled bacon and you won’t be disappointed. Ground turkey or chicken sausage work beautifully, too, especially if you’re looking for a leaner option.

Load Up On Veggies: Sun-dried tomatoes add an incredible depth of flavor here, and roasted sweet potatoes are a fantastic swap if mushrooms aren’t your thing. Spinach, zucchini, and diced tomatoes are all fair game—just make sure to sauté them first to avoid a watery casserole.

Make it Eggier: Bump up to 12 eggs instead of 10 for a fluffier, more egg-forward breakfast bake that yields a few extra servings. Perfect if you’re feeding a larger crowd or want even more protein per slice.

Create Breakfast Muffins: Grease a muffin tin and evenly distribute the cooked sausage and veggie mixture among the cups, then pour the whisked eggs over top. Bake at 350°F for 18-22 minutes for perfectly portioned, grab-and-go breakfast muffins that are ideal for busy mornings.

Whole30 breakfast casserole with sausage, eggs, mushrooms, and spinach in a white baking dish, garnished with fresh basil.

Frequently Asked Questions

Can I make this breakfast bake ahead of time?

Heck, yes! Assemble the entire casserole the night before, cover tightly with foil, and refrigerate. In the morning, let it sit at room temperature while your oven preheats, then bake as directed. You may need to add 5-10 extra minutes since it’s starting cold.

What can I substitute for the sausage?

Tons! Any ground breakfast meat works here—try bacon, ground turkey, or chicken sausage. Just make sure it’s Whole30 compliant if you’re following the program (watch for added sugars and non-compliant ingredients).

Do I have to sauté the vegetables first?

I know it’s tempting to take shortcuts, but yes, you should, and here’s why—raw vegetables release moisture as they cook, which can make your breakfast bake watery and soggy. Sautéing them first concentrates the flavors and ensures a perfectly textured casserole.

Can I add cheese to this recipe?

If you’re not doing Whole30, sharp cheddar or pepper jack would be delicious! Stir in about 1 cup of shredded cheese before baking.

More Tasty Breakfast Recipes

Making changes to a recipe can result in recipe failure. Any substitutions or variations listed are simple changes that I believe will work in this recipe, but results are not guaranteed.

Slice of Whole30 breakfast bake with sausage, eggs, spinach, and bell peppers on a cream plate with a fork
Recipe By: Cheryl Malik
4.96 from 68 votes

Whole30 Breakfast Casserole with Sausage and Eggs (Keto)

Prep 15 minutes
Cook 35 minutes
Total 50 minutes
This Whole30 breakfast casserole with eggs and sausage is loaded with savory sausage, fluffy eggs, and perfectly seasoned vegetables—all baked together into one satisfying, make-ahead meal. It's amazing for busy mornings, meal prep, or feeding a ravenous family!
Cheryl MalikCheryl Malik
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9 servings

Equipment

  • Large bowl
  • Medium skillet
  • 9×13 baking dish
  • Medium bowl

Ingredients

  • 1 pound Whole30-compliant breakfast sausage see below for recipe
  • 3 cups white mushrooms sliced
  • olive oil as needed
  • 6 green onions sliced
  • 3 Roma tomatoes seeded and diced
  • 1 tablespoon fresh basil chopped, or 2 teaspoons dried basil
  • 12 ounces frozen chopped spinach thawed
  • 1 ½ teaspoons salt
  • 10 large eggs

For Homemade Whole30-Compliant Breakfast Sausage

  • 1 pound ground pork
  • 1 teaspoon dried sage
  • 1 teaspoon salt
  • ½ teaspoon ground black pepper
  • 1 pinch dried marjoram
  • 1 pinch crushed red pepper flakes
  • 1 pinch ground cloves

Instructions
 

Make the Whole30-Compliant Breakfast Sausage

  • Combine all ingredients in a medium bowl and mix well with your hands. Use in recipe right away or keep in an airtight container for 1 day in the fridge.

Make the Whole30 Breakfast Bake

  • Preheat oven to 350º Fahrenheit.
  • In a medium skillet over medium heat, brown and crumble sausage. Add olive oil if necessary.
  • Add mushrooms and cook about 5 minutes or until soft, stirring occasionally. Add remaining vegetables, herbs, and salt and cook about 2 minutes or until slightly softened and well combined. Pour mixture into baking dish.
  • Crack eggs into a medium bowl and whisk well. Pour over sausage-vegetable mixture and bake 25-30 minutes or until a knife, inserted in the center, comes out clean. Serve warm.

Video

Add Cheese: If you’re not doing Whole30 and want to add cheese, sharp cheddar or pepper jack would be incredible stirred in before baking.
Sausage Substitutions: Any ground breakfast sausage works here—pork, turkey, chicken, or even compliant plant-based crumbles if that’s your thing. Just make sure it’s Whole30 approved if you’re following the program (watch for added sugars and non-compliant ingredients).
Vegetable Variations: The combination of bell peppers, onions, mushrooms, and spinach is classic, but feel free to swap in zucchini, diced sweet potato, cherry tomatoes, or kale. Just remember to sauté everything first to remove moisture and ensure even cooking.
Boost the Protein: Want even more staying power? Add an extra egg or two, or increase the sausage to 1.5 pounds. The beauty of a breakfast bake is that it’s incredibly flexible.
Make-ahead Instructions: Assemble the entire casserole the night before (through step 4), cover tightly with foil, and refrigerate overnight. In the morning, let it sit at room temperature while your oven preheats, then bake as directed—you may need to add 5-10 extra minutes to the baking time since it’s starting cold.
Storage and Reheating: Store leftovers in an airtight container for up to 5 days. It reheats beautifully in the microwave (60-90 seconds per portion) or in the oven at 350°F covered with foil for about 15 minutes.
Freezer-Friendly: Wrap individual portions tightly in plastic wrap and foil, then freeze for up to 3 months. Thaw overnight in the fridge and reheat as usual, or microwave from frozen for 2-3 minutes.

Approximate Information for One Serving

Serving Size: 1servingCalories: 268calProtein: 19gFat: 20gSaturated Fat: 6gTrans Fat: 1gCholesterol: 243mgSodium: 795mgPotassium: 573mgTotal Carbs: 5gFiber: 2gSugar: 2gNet Carbs: 3gVitamin A: 6491IUVitamin C: 8mgCalcium: 116mgIron: 3mg
Nutrition Disclaimers
Number of total servings shown is approximate. Actual number of servings will depend on your preferred portion sizes.
Nutritional values shown are general guidelines and reflect information for 1 serving using the ingredients listed, not including any optional ingredients. Actual macros may vary slightly depending on specific brands and types of ingredients used.
To determine the weight of one serving, prepare the recipe as instructed. Weigh the finished recipe, then divide the weight of the finished recipe (not including the weight of the container the food is in) by the desired number of servings. Result will be the weight of one serving.

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Cheryl Malik

In addition to being a certified health coach, certified yoga instructor, and mom of 3, Cheryl is also the recipe developer, editor-in-chief, food photographer, and passionate foodie behind 40 Aprons. Having spent the last 10+ years as a food blogger, she's become known for her flavorful recipes, detailed instructions, gorgeous photography, and down-to-earth approach to food and cooking in general.

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138 Comments

  2. I love the idea of this recipe!!!I am not on any specific diet, but am looking for healthier recipes to lose a few and not feel like I’m starving myself to do it. This looks so perfect!!! I plan on making this Monday morning, subbing the sausage with turkey, and eating the leftovers for breakfast all week! Super excited! Thanks for sharing!!5 stars

    Reply

    1. Here’s what I’d do: make everything ahead but DON’T add the eggs yet. In the morning, crack all the eggs, pour over, and bake. That should only take you a couple minutes in the morning and will help the dish come out super fresh!5 stars

      Reply

  5. Just made this for dinner on day 25 of my first Whole30, and it is the best thing we’ve had yet! Incredible. Thank you for sharing!

    Reply

  7. This was very flavorful and delicious! I added garlic powder and substituted pork with ground turkey and added more veggies that I personally like. Thanks for sharing the recipe. =)5 stars

    Reply

  8. Hello! I’m going to make this recipe this weekend. I have fresh spinach, do you recommend cooking it first before putting it in the casserole? And also can you recommend a substitute for marjoram?

    Reply

    1. I would chop it and sauté it lightly first, yes, but make sure you squeeze alllllll of the water out! You’d be fine with just chopping it and leaving it raw, too. Do you have poultry seasoning? That works to replace the marjoram too. There’s another whole30 breakfast sausage recipe on my blog, if you go to 40aprons.com (it should be on the homepage!), if you want to check it out. I hope you like it, and let me know if you have any other questions!

      Reply

  9. 5 STARS (The fifth star won’t light up.) I made this exactly as written for Easter yesterday. It was truly the best tasting egg dish I’ve had and everyone loved it. We are not doing Whole 30, I just thought this looked outstanding, and it was! Next time I’ll include some other veggies. Thanks for showing something like this can be great even without cheese… 🙂4 stars

    Reply

    1. Yay! I’m so glad you enjoyed it, even though you’re not on a Whole30! “Showing something like this can be great even without cheese” is basically the best compliment ever, ha! Thank you for 5 stars, despite our funky recipe plugin quirks 😉

      Reply

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