Oh, the joys of Christmas morning! The wrapping paper flying around, the kids squealing with delight, and the cozy aroma of the Christmas overnight breakfast casserole wafting from the kitchen. Can it get any better?

An overnight breakfast casserole is one of the best ways to make your Christmas morning as stress-free and enjoyable as possible. You can put on your favorite holiday tunes, pour yourself a cup of coffee, and let the casserole do its magic in the oven while you join the festivities.
Bread, eggs, ham, onions, peppers, and cheese come together for an easy-to-make casserole with a souffle texture. It is flavored with peppers and onions, giving it a bit of a Denver omelet feel. This easy casserole is sure to become a tradition with your family!
In this post, we’ll dive into the ins and outs of this festive dish. We’ll cover everything from the ingredients to the step-by-step instructions and even a few tips and tricks to make your casserole the star of your Christmas morning or holiday brunch.
Looking for more Christmas breakfast ideas? Try apple French toast breakfast casserole, chicken and waffle casserole, or Christmas bagels.
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🎄Ingredient Notes
For exact amounts needed see the recipe card below
- Eggs
- Milk
- Dijon mustard
- Ham: If you’ve got leftovers from Christmas Eve dinner, use them.
- Onion
- Bell pepper: Use both red and green bell peppers for festive cheer!
- White bread
- Cheese: I like combining cheddar and pepperjack cheese for a creamy and spicy blend. But feel free to use your favorites.
🥣Creating Your Christmas Overnight Breakfast Casserole
- First, whisk your eggs, milk, and Dijon mustard in a large bowl, ensuring they are well combined.
- Reserve a quarter of your diced bell peppers for later. Then, stir the remaining peppers, ham, onion, and bread into your egg mixture. You can use your hands or a big spoon for this part.
- Now, butter up a 9×13 baking dish and pour in the mixture. Top it off with the cheeses and the reserved bell peppers. At this point, your casserole is ready to chill out in the fridge. The overnight rest allows all the flavors to meld together.
- Preheat your oven to 350 degrees the following day and let the casserole sit on the counter for about 30 minutes. This helps take the chill off the casserole, ensuring even baking.
- Then, it’s in the oven for 55-60 minutes until golden brown. If it starts to brown too quickly, don’t panic! Just cover it with some aluminum foil.
🤶Serving Up The Christmas Morning Magic
Here are a few ideas on how to make your casserole look as mouth-watering as it tastes.
- Keep it classic: There’s something comforting about sticking to the classics, don’t you agree? Serve your casserole in the baking dish with a large, fancy serving spoon. It’s simple, homespun, and oh-so-Christmassy!
- Dish it out: Feeling a bit more fancy? Divide the casserole into individual portions and serve them on colorful Christmas-themed plates.
- Add some color: Sprinkle some chopped fresh herbs on top for a pop of color. It will look pretty, and herbs like parsley or chives can add a lovely fresh flavor to your rich, hearty casserole.
- The sides matter: Don’t forget about sides! I like to serve mine with a fresh fruit salad or warm and tasty cinnamon rolls.
💭How to Store
Store your festive casserole in the refrigerator for up to 4 days. Cover it tightly with plastic wrap or transfer it to an airtight container.
If you’ve got more left than you can handle, freeze it for up to 2 months. Just divide it into individual portions, wrap them in foil, and pop them into freezer-safe bags. Reheat in the oven when you’re ready to enjoy them again.
When you’re ready to revisit the Christmas delight, reheat your casserole in the oven at 350°F until it’s warm. If you’re heating from frozen, give it more time to ensure it’s heated through.
⭐Variations & Tips
Be sure to check out the step by step instructions
- Not a fan of ham? No problem! Feel free to swap it out with sausage or bacon. Or make a meatless breakfast casserole.
- For those who like it hot, try adding diced jalapenos or green chiles.
- I typically use sandwich bread, but you can experiment with other types. Croissants, Italian bread, brioche, or a mix of different breads can add an exciting twist to the texture and flavor.
📝FAQ
Absolutely! Just make sure to use a gluten-free bread. There are many great options out there these days so that you will experience the flavor and texture.
For sure! Use almond, soy, or oat milk instead of regular milk. It might slightly alter the taste, but not enough to make a significant difference.
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Christmas Overnight Breakfast Casserole Recipe
Ingredients
- 9 eggs
- 3 cups milk
- 2 teaspoons Dijon mustard
- 1 pound diced ham
- 1 onion diced
- 1 green bell pepper diced, divided
- 1 red bell pepper diced, divided
- 9 slices white bread torn into pieces
- 1 cup shredded sharp cheddar cheese
- 1 cup shredded pepper jack cheese
- Green onions for garnish
Instructions
- Whisk together your eggs, milk, and Dijon mustard in a medium bowl.9 eggs, 3 cups milk, 2 teaspoons Dijon mustard
- Reserve a quarter of your diced red and green bell pepper.1 green bell pepper, 1 red bell pepper
- Add ham, onion, peppers, and bread to the egg mixture.1 pound diced ham, 1 onion, 9 slices white bread
- Butter or spray a 9×13 casserole dish. Pour in the mixture.
- Top the casserole with the cheeses and the reserved bell peppers.1 cup shredded sharp cheddar cheese, 1 cup shredded pepper jack cheese
- Cover with plastic wrap and place in the fridge overnight or up to 12 hours.
- When ready to bake, preheat oven to 350 degrees. Let the casserole sit on the counter for 30 minutes to take the chill off while the oven preheats.
- Bake the casserole at 350 for 55-60 minutes. If it begins to brown too quickly, cover it with foil.Green onions for garnish
Notes
- Store leftovers in the fridge for up to 5 days.
- You can swap out the meat in this dish; try it with breakfast sausage or bacon!
- You can spice this up by adding diced jalapenos or green chiles.
- Use whatever cheese you like. Swiss also works well.
- I use sandwich bread, but any bread would work. Try croissants, Italian bread, or brioche, or add more than one kind of bread!
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Nutrition Information
Nutrition facts are estimates.