Hey everyone, and welcome to scooks.com! I am SO excited to share this recipe with you today. Seriously, get ready to rethink everything you thought you knew about brunch. We’re talking about a breakfast casserole, but this isn’t your grandma’s standard bread-and-egg bake (no offense, Grandma!). We are taking things to a whole new level of delicious. Imagine this: flaky, buttery croissants soaking up a rich, savory egg custard, studded with crispy, salty prosciutto and swirled with creamy, herby Boursin cheese. It’s baked on a sheet pan until it’s golden, puffed, and absolutely irresistible. This sheet pan croissant breakfast casserole recipe is my secret weapon for holidays, lazy weekends, and basically any time I need to feed a hungry crowd with minimal effort but maximum ‘wow’ factor. Let’s get cooking!
Why You’ll Love This Breakfast Casserole Recipe
I could go on and on, but honestly, this might just be the most perfect breakfast casserole recipe ever created. Here are a few reasons why I know you’ll fall head over heels for it.
Effortlessly Elegant
This casserole looks like you spent all morning in the kitchen, but it comes together so quickly! The golden, puffed croissants and crispy prosciutto make for a stunning presentation. It’s the kind of dish that gets oohs and aahs when you bring it to the table, and nobody needs to know how easy it was.
Make-Ahead Magic for Stress-Free Mornings
This is probably my favorite part. You can assemble the entire thing the night before, pop it in the fridge, and then just bake it off in the morning. Can you imagine waking up on a holiday morning, coffee in hand, with breakfast already prepped? It’s a total game-changer for stress-free hosting.
Incredible Flavor and Texture in Every Bite
We’re talking layers of amazingness here. You get the soft, custardy interior of the croissants and the crispy, golden tops. Then there’s the salty bite from the prosciutto, the creamy tang from the Boursin, and the nutty richness of Gruyère. It’s a symphony of textures and flavors that is just pure comfort and joy.
Completely Customizable to Your Taste
Don’t love prosciutto? Swap it for bacon or sausage. Not a fan of Gruyère? Use cheddar! This recipe is an amazing template. You can easily tweak it with your favorite meats, cheeses, and veggies to make it your own signature brunch dish. What will you put in yours?
Ingredients for the Croissant Breakfast Casserole
One of the best things about this recipe is that it uses simple, high-quality ingredients to create something truly special. You don’t need a massive shopping list to achieve brunch perfection!
For the Casserole Base:
- 6-8 Large Croissants: Preferably a day or two old, torn into 1- to 2-inch pieces.
- 4 ounces Prosciutto: Thinly sliced.
- 1 ½ cups Gruyère Cheese: Freshly shredded. You can also use a good white cheddar.
- 1 cup Fresh Spinach or 1/2 cup Chopped Asparagus: Your choice of fresh greens!
For the Egg Custard:
- 8 Large Eggs
- 1 ½ cups Whole Milk
- ½ cup Heavy Cream
- 5.2-ounce package Boursin Garlic & Fine Herbs Cheese: Softened to room temperature.
- 1 tablespoon Dijon Mustard
- ½ teaspoon Salt
- ½ teaspoon Black Pepper
- ¼ teaspoon Nutmeg: Freshly grated is best!
Ingredient Notes & Substitutions:
Got questions? I’ve got answers! It’s super easy to adapt this fantastic breakfast casserole recipe.
- What can I use instead of croissants? While croissants make it extra decadent, you can substitute them with about 8-10 cups of cubed brioche, challah, or even a sturdy French bread. The key is to use bread that’s a bit dry so it can soak up all that delicious custard.
- Best prosciutto substitutes (including vegetarian options). Crispy, crumbled bacon is a classic choice. Cooked and crumbled sausage or diced ham also work beautifully. For a vegetarian version, try 8 ounces of sautéed mushrooms with a pinch of thyme, or some sun-dried tomatoes for a pop of flavor.
- Don’t have Boursin? Try this! No problem! You can mimic the flavor by mixing 5 ounces of softened cream cheese with 1 minced garlic clove, 1 teaspoon of dried chives, and ½ teaspoon of dried dill. It’s a great dupe!
- Other cheese varieties that work well. Feel free to experiment! A sharp white cheddar, Swiss cheese, Monterey Jack, or even a mix of Parmesan and mozzarella would be delicious.
Step-by-Step Instructions
Alright, let’s build this beauty. Following these simple steps will guarantee a perfect result every time.
Step 1: Prepare the Pan and Crisp the Prosciutto
First things first, preheat your oven to 375°F. Line a large, rimmed baking sheet (about 18×13 inches) with parchment paper. Arrange the prosciutto slices in a single layer on the prepared pan. Bake for 8-10 minutes, or until it’s crispy. Transfer the crispy prosciutto to a plate and let it cool, then roughly crumble it. Don’t wash the pan!
Step 2: Arrange the Croissants and Veggies
Tear your croissants into bite-sized pieces and scatter them evenly across that same baking sheet. You want to use the pan drippings from the prosciutto for extra flavor! Sprinkle the crumbled prosciutto and your chosen veggies (spinach or asparagus) over the croissants.
Step 3: Whisk the Creamy Egg Custard
In a large bowl, whisk together the eggs, whole milk, and heavy cream until they’re well combined. Add the softened Boursin cheese, Dijon mustard, salt, pepper, and nutmeg. Whisk vigorously until the Boursin is mostly broken up and the mixture is smooth. It’s okay if a few small lumps of cheese remain—they’ll melt into delicious, creamy pockets as it bakes!
Step 4: Assemble the Casserole
Carefully and evenly pour the egg custard mixture all over the croissants on the baking sheet. Gently press down on the croissants with a spatula to help them absorb the liquid. Now, sprinkle the shredded Gruyère cheese evenly over the top. (Make-Ahead Note: At this point, you can cover the pan tightly with plastic wrap and refrigerate it for up to 24 hours.)
Step 5: Bake Until Golden and Puffed
Bake for 30-35 minutes (or 40-45 minutes if baking from cold) until the casserole is puffed, golden brown, and the center is set. A knife inserted into the middle should come out clean.
Step 6: Garnish and Serve
Let the casserole cool on the pan for about 5-10 minutes before slicing. This helps it set up perfectly. Garnish with some fresh chives or parsley if you’re feeling fancy, and serve warm. Enjoy the compliments!
Baker’s Tips for Success
Want to absolutely nail this croissant breakfast casserole recipe? Here are my top tips for guaranteed success.
- Use Day-Old Croissants for the Best Texture: Fresh, soft croissants can turn mushy. Stale, day-old croissants are thirstier and do a much better job of soaking up the custard while maintaining some of their structure.
- Don’t Skip Crisping the Prosciutto: This is a non-negotiable step! Baking the prosciutto first ensures it stays crispy and delightful. If you add it raw, it will just steam in the casserole and become chewy.
- The Secret to a Never-Soggy Casserole: The key is the bread-to-custard ratio and using stale bread. If you’re adding lots of veggies, especially ones with high water content like spinach or mushrooms, make sure to cook them down first to release their moisture before adding them to the casserole.
- How to Know When It’s Perfectly Baked: The casserole should be visibly puffed and golden across the top. The center shouldn’t jiggle when you gently shake the pan. For 100% certainty, an instant-read thermometer inserted into the center should register 160°F.
- Let It Rest Before Slicing: I know it’s tempting to dive right in, but letting the casserole rest for 5-10 minutes is crucial. It allows the custard to finish setting, which means you’ll get clean, beautiful slices instead of a runny pile.
Storage, Freezing, and Reheating Instructions
This recipe is fantastic for leftovers, if you have any! Here’s how to store and enjoy it later.
How to Store Leftovers
Allow the casserole to cool completely, then cover the pan tightly with foil or transfer slices to an airtight container. It will keep beautifully in the refrigerator for up to 3 days.
Can I Freeze This Breakfast Casserole? (Baked and Unbaked)
Yes, you can!
* To freeze unbaked: Assemble the casserole completely on the sheet pan, but don’t bake it. Wrap it tightly in a layer of plastic wrap, followed by a layer of foil. It can be frozen for up to 2 months. Thaw it overnight in the refrigerator before baking as directed (it may need an extra 10-15 minutes).
* To freeze baked: Let the casserole cool completely. You can freeze it whole or cut it into individual portions. Wrap each portion tightly in plastic wrap and foil and freeze for up to 3 months.
The Best Way to Reheat for That “Just-Baked” Taste
The oven is your best friend here! To reheat, place slices on a baking sheet and warm them in a 350°F oven for 10-15 minutes, or until heated through. This helps re-crisp the top. A microwave will work in a pinch, but you’ll lose the crispy texture.
Frequently Asked Questions (FAQ)
Can I prepare this breakfast casserole recipe the night before?
Absolutely! That’s one of the best things about it. Just follow the instructions through Step 4, cover it tightly, and refrigerate overnight. You may need to add 10-15 minutes to the baking time since it will be starting from cold.
How do I make this recipe vegetarian?
It’s simple! Just omit the prosciutto. To replace that savory, salty element, I recommend adding 8 ounces of sautéed mushrooms, a handful of sun-dried tomatoes, or some roasted red peppers.
Can I use a 9×13-inch baking dish instead of a sheet pan?
Yes, you can definitely use a standard 9×13-inch baking dish. The casserole will be thicker, so you’ll likely need to increase the baking time to 45-55 minutes. Just make sure the center is fully set before pulling it from the oven.
What should I serve with this casserole?
This casserole is a pretty complete meal on its own, but it pairs wonderfully with a simple fruit salad to add a fresh, sweet contrast. A light green salad with a zesty vinaigrette also works well to cut through the richness.
My casserole came out watery. What did I do wrong?
A watery casserole is usually due to one of three things: 1) Using vegetables with high water content (like spinach or mushrooms) without pre-cooking them to release moisture. 2) The egg-to-liquid ratio was off. 3) It was simply underbaked. Make sure the center is fully set and not jiggly before you take it out of the oven!
Conclusion
And there you have it—a truly show-stopping breakfast casserole recipe that’s destined to become a new family favorite. It’s rich, savory, and so incredibly satisfying. I really hope you give this recipe a try for your next brunch, holiday gathering, or special weekend breakfast. It’s the perfect way to show some love through food!
If you make this Sheet Pan Croissant Breakfast Casserole, please let me know how it turned out! I’d love for you to leave a comment and a rating below. Your feedback is so helpful for me and for other readers! Happy cooking!
I am a passionate recipe developer and food enthusiast specializing in heart-warming traditional dishes and simple, everyday meals. My goal is to inspire you to find joy and confidence in the kitchen through my easy-to-follow recipes.