This fluffy Oven-Baked Omelet Casserole is the easiest way to make a Denver omelet. It contains protein-packed eggs, tender ham, fresh bell peppers, and wholesome mushrooms. It is perfect for breakfast, brunch, or supper. Make this ahead of time and store it in the fridge for a quick breakfast on busy mornings; perfect for back to school. It takes less than 15 minutes to prep, then pop it in the oven to bake. Set the timer and forget it. Plus, it tastes SO good.
This breakfast egg casserole is such an EASY way to prepare eggs. It doesn't get any easier, plus it's healthy, high in protein, and low in carbs.
This is an easy breakfast idea you should remember when you are pressed for time. It can easily be adjusted to make for a larger or smaller crowd.
This Western egg casserole is filling and satisfying. It bakes up to a puffy, golden casserole that your whole family will love. Eat it as is, or put it inside a wrap for a healthy breakfast.
Plus, you don't have to stand at the stove waiting for it to cook like you do when cooking a regular omelet.
For a traditional omelet, try my Spinach Mushroom Omelette With Feta Cheese. And for another easy breakfast casserole, try my Baked Overnight Eggnog French Toast Casserole with Streusel Topping.
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🧡 Why You Will Love This Recipe
- Convenient: This fluffy omelet is perfect for busy mornings. You can make it ahead of time and store it in the fridge, then reheat it quickly for a delicious and nutritious breakfast.
- Easy to make: This Denver omelet casserole is incredibly easy to make, with less than 15 minutes of prep time. Simply mix together the ingredients and pop it in the oven to bake.
- Protein-packed: Eggs and ham are excellent sources of protein, making this dish a great choice for those looking to increase their protein intake.
- Delicious: The combination of fluffy eggs, ham, fresh bell peppers, and mushrooms creates a flavorful dish that your whole family will love.
- Versatile: This healthy breakfast casserole can be served for breakfast, brunch, or supper.
- Meal prep: Once cooled, transfer individual servings into an airtight container and store them in the refrigerator for up to 4 days. To reheat, simply microwave the individual servings for 30-60 seconds or until heated through.
🥘 Ingredients
If these simple ingredients are not already in your kitchen, they can be easily found at your local grocery store.

- Eggs. I used large eggs, including the egg yolks.
- Milk. I used 1% milk, but you can use almond milk, coconut milk, or oat milk.
- Shredded cheese. I used white cheddar cheese, but you can use your favorite kind. It would be great with sharp cheddar cheese, gouda, swiss, mozzarella, or even feta.
- Diced ham. Ham goes great in an omelet; just make sure it is already pre-cooked. You can use leftover Baked Ham or leftover Double Smoked Ham. You could also use Air Fryer Bacon, thinly sliced cooked steak, Air Fryer Sausage, Smoked Sausage, leftover chicken from Air Fryer Chicken Thighs, Air Fryer Chicken Breasts, Instant Pot Chicken Breasts, Smoked Chicken Breasts or Smoked Chicken Thighs, or even Smoked Salmon.
- Mushrooms and bell peppers: (I used orange peppers, but you could also use green bell peppers, or red peppers. You can also use spinach, tomatoes, and leeks. Look in your fridge and use up anything that you have sitting in the crisper.
This baked omelet casserole is easy to modify to suit your tastes. Are you a vegetarian? Leave out the meat. Do you want to make it healthier? Add more vegetables. The sky is the limit for what you can do with this baked oven omelet.
See the printable recipe card for exact measurements and a complete list of ingredients.
🍳 Instructions
This oven-baked omelet is very easy to make and takes very little prep time.
First of all, preheat the oven to 350 degrees F.
Next, whisk together the eggs in a large bowl. You can also use a hand mixer if desired.


Next, add milk, seasoning salt, and black pepper. Whisk to combine.


Then, add the diced ham and shredded cheddar cheese.


Next, add the bell peppers and mushrooms. Stir to combine.


Finally, pour egg mixture into a greased 9 x 12 casserole dish.


Bake for 45 minutes at 350 degrees, until the top is golden brown and the eggs are set.

Cut the casserole into squares and serve.
Enjoy.

💭 Expert Tips
- Whisk the eggs well to ensure that they are fully combined and aerated. This will help create a light and fluffy texture.
- Use a casserole dish that is the appropriate size. If the dish is too large, the omelet may become dry and overcooked.
- Allow the omelet to rest for a few minutes before serving to help it set.
- Consider adding spinach, tomatoes, or onions to give the dish extra flavor and nutrition.
- Don't overcook the omelet. It should be slightly firm to the touch but still moist and tender.
- If using vegetables that release moisture, such as fresh mushrooms or tomatoes, consider sautéing them in a separate pan before adding them to the egg mixture. This will prevent the omelet from becoming watery.
- Store leftovers in an airtight container in the refrigerator for up to 3 days. To reheat, microwave on high for 30 seconds to 1 minute, or until heated through.
📖 What else can you put in an omelet?
- Crisp bacon.
- Diced tomatoes or cherry tomatoes.
- Leeks.
- Fresh herbs.
- Spinach.
- Green onions.
- Garlic.
- Zucchini.
- Celery.
🥗 Side dishes
- Avocado.
- Fruit.
- Tomatoes.
- Hash browns.
- Crispy oven-roasted potatoes or hashbrowns.
- Salad.
- Air Fryer Toast.
- English muffin.
- Buttermilk Sheet Pan Pancakes.
- Baked Overnight Eggnog French toast.
🥞 More Breakfast Recipes
❓ FAQs
Yes, you can substitute whole eggs with egg whites if you're looking for a lower-calorie option. Just be aware that the texture may differ slightly.
Yes, you can make this omelet casserole ahead of time and store it in the fridge. Reheat it in the oven or microwave before serving.
The omelet is cooked when it is puffed up, golden brown, and a toothpick inserted in the center comes out clean. This should take about 45 minutes in the oven.
Yes, you can adjust the seasoning to your liking. You can add more salt, pepper, or any other spices you prefer.
👪 More Easy Recipes You'll Love
If you’ve tried this Fluffy Oven-Baked Omelet Casserole or any other recipe, please take a moment to rate the recipe 🌟🌟🌟🌟🌟 and leave a comment below with your thoughts!

Easy Fluffy Oven-Baked Omelet Casserole Recipe
Ingredients
- 12 eggs
- 1½ cup milk
- ¾ teaspoon seasoning salt
- ¼ teaspoon black pepper
- 1½ cup diced ham
- 1 cup shredded cheddar cheese
- 1½ cup finely chopped bell peppers
- 1 cup canned mushrooms drained
Instructions
- Preheat oven to 350 degrees F.
- Whisk together the eggs in a large bowl.12 eggs
- Add milk, seasoning salt, and black pepper. Whisk to combine.1½ cup milk, ¾ teaspoon seasoning salt, ¼ teaspoon black pepper
- Stir in diced ham, cheddar cheese, bell peppers, and mushrooms. Stir to combine.1½ cup diced ham, 1 cup shredded cheddar cheese, 1½ cup finely chopped bell peppers, 1 cup canned mushrooms
- Pour into a greased 9 x 12 baking dish.
- Bake at 350 degrees F for 45 minutes until golden brown on top and eggs are set.
- Cut the casserole into squares and serve.
- Enjoy!
Notes
- Whisk the eggs well to ensure that they are fully combined and aerated. This will help create a light and fluffy texture.
- Use a casserole dish that is the appropriate size. If the dish is too large, the omelet may become dry and overcooked.
- Allow the omelet to rest for a few minutes before serving to help it set.
- Consider adding spinach, tomatoes, or onions to give the dish extra flavor and nutrition.
- Don't overcook the omelet. It should be slightly firm to the touch but still moist and tender.
- If using vegetables that release moisture, such as fresh mushrooms or tomatoes, consider sautéing them in a separate pan before adding them to the egg mixture. This will prevent the omelet from becoming watery.
- Store leftovers in an airtight container in the refrigerator for up to 3 days. To reheat, microwave on high for 30 seconds to 1 minute, or until heated through.
Lynn
I've made this a few times now and always comes out perfectly. I use red, orange and green bell peppers, and top with green onions. I stir halfway through, and cook it at 355 since my oven seems to take longer to cook this. Thank you for the awesome recipe!!
Jeri Walker
I'm so glad you like this recipe, Lynn! Thank you for sharing your tips, and thank you for coming back to rate the recipe and leaving a comment! I appreciate it! 🙂
Brenda
WONDERFUL!!! I served to weekend company (2 people that we had only met) and they couldn’t stop raving about this!!!
Thank you for sharing!
Jeri
Thank you for trying our oven baked omelet casserole, Brenda. I'm so glad you and your guests enjoyed it! It's one of our favorites! Thanks for taking the time to come back and leave a comment! 🙂
Mihaela | https://theworldisanoyster.com/
I used to make oven-baked omelettes (when I had more time at hand, LOL), and spinach and courgettes were always among the ingredients. Broccoli too, since my fussy eater likes it, paradoxically:) You just reminded me how nicely they turn up!
Jean
when I first saw the photo I knew it already looks delicious and can be served on occasions too!
Nora
Yum! This looks so delicious! Can't wait to try it out and have a bite! Thank you for sharing!
Freya
How delicious and cheesy this looks! And so easy too!
Kay
A great recipe that even my fussy eater daughter enjoyed! Is now a weekly meal in our house.
Amy
This was such a great idea and honestly, so much easier, especially when I'm feeding quite a few people. I especially loved it because it enabled me to get rid of some of the vegetables that were in the fridge. They were fluffy as you said and you're right, high in protein and low in carbs is such an added bonus.
Linda
This omelet casserole is delicious! So flavorful and easy to prep and clean up.