Fluffy Croissant Breakfast Delight

Breakfast casseroles are a delightful way to simplify your morning routine, especially when hosting brunch. This Croissant Breakfast Casserole, featuring flaky croissants, savory ham, fresh spinach, and melted cheese, exemplifies both ease and exquisite taste. With the convenience of overnight preparation, you can simply pop it in the oven in the morning and serve a spectacular brunch with minimal fuss.

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There’s something truly magical about a breakfast casserole – it transforms a chaotic morning meal into a relaxed, enjoyable experience. Among my favorite recipes, this Croissant Breakfast Casserole holds a special place. The harmonious blend of buttery croissants, savory ham, earthy spinach, and rich, melted cheese creates a dish that is hot, hearty, and utterly irresistible. It’s the kind of comfort food that warms you from the inside out, making it perfect for any gathering, from a casual family breakfast to an elaborate holiday brunch.

What truly sets this Croissant Breakfast Casserole apart is its incredible make-ahead convenience. Imagine waking up, perhaps a little earlier than usual, to the simple task of sliding a pre-assembled dish into the oven. Then, you can return to your cozy bed or enjoy a leisurely cup of coffee while the aroma of a delicious breakfast fills your home. Approximately an hour later, a golden-brown, bubbly casserole emerges, ready to be enjoyed. This effortless preparation means less stress on busy mornings and more quality time with loved ones, making it an absolute game-changer for anyone who loves a homemade breakfast but dreads the morning rush.

Essential Ingredients for Your Croissant Breakfast Casserole

Crafting this irresistible breakfast casserole begins with selecting fresh, high-quality ingredients that harmonize beautifully to create a symphony of flavors and textures. Here’s a detailed look at what you’ll need:

• Cooking Oil or Butter: Essential for sautéing the onions and ham, adding a foundational layer of flavor to the dish. Butter will impart a richer, more luxurious taste.
• Ham: Approximately 10 ounces of diced ham forms the hearty core of this casserole. Leftover holiday ham works perfectly, but pre-cooked diced ham from the grocery store is equally convenient. Consider smoked ham for an extra depth of flavor.
• Onions: About 1 cup of chopped sweet onions, such as Spanish or Vidalia, provides a subtle sweetness and aromatic depth once sautéed until translucent. They mellow beautifully during cooking.
• Cooked Baby Spinach: You’ll need about ½ cup of cooked baby spinach, thoroughly squeezed to remove any excess water. This step is crucial to prevent the casserole from becoming watery. Spinach adds a lovely hint of green and a dose of nutrients.
• Eggs: Six large eggs form the rich, custardy base that binds all the ingredients together. They create that delightful, fluffy texture in every bite.
• Milk: One cup of milk contributes to the creamy consistency of the egg custard, ensuring the croissants soak up plenty of liquid for a moist interior. Whole milk is recommended for the best richness.
• Heavy Whipping Cream: Adding a cup of heavy whipping cream elevates the casserole to a truly luxurious level. It imparts an unmatched richness and velvety texture, making each spoonful feel indulgent.
• Dijon Mustard: Two tablespoons of Dijon mustard are a secret weapon, adding a sophisticated tang that cuts through the richness of the cheese and ham. It subtly enhances the overall flavor profile without overpowering it.
• Kosher Salt and Pepper: These fundamental seasonings are vital for balancing and enhancing all the flavors within the casserole. Adjust to taste, but start with ½ teaspoon of salt for a good base.
• Gruyere Cheese: Six ounces of shredded Gruyere cheese is my top recommendation. Its nutty, savory, and wonderfully melting qualities are simply divine in this casserole. However, any good easy-melting cheese, such as cheddar, Monterey Jack, or Fontina, can be used as a delicious alternative.
• Green Onions (Optional Garnish): A sprinkle of freshly chopped green onions just before serving adds a pop of color and a mild, fresh onion flavor, offering a lovely counterpoint to the rich casserole.
• Mini Croissants: You’ll need approximately 15-16 mini croissants, or 8 larger croissants cut into quarters. The flaky, buttery layers of the croissants are what make this casserole truly special, absorbing the egg custard and becoming wonderfully tender. Stale croissants actually work best as they absorb liquid more readily without becoming soggy.

Crafting Your Croissant Breakfast Casserole: Step-by-Step Guide

Follow these simple steps to assemble your incredible make-ahead breakfast casserole. Remember, the key to success is in the overnight soak!

1. Prepare Your Baking Dish: Begin by lightly spraying a 9×13-inch baking dish with nonstick cooking spray. This crucial step ensures your delicious casserole won’t stick, making serving and cleanup a breeze. Set the prepared dish aside.
2. Sauté the Aromatics: Heat a large skillet over medium heat. Once warm, add a tablespoon of cooking oil or butter. Add the chopped onions and sauté them gently until they become beautifully translucent and softened, which usually takes about 5-7 minutes. Avoid browning them too much; we’re looking for tender sweetness.
3. Incorporate the Ham: Add the diced ham to the skillet with the sautéed onions. Stir them together and cook for another 2-3 minutes, just until the ham is warmed through and lightly browned at the edges, releasing its savory aroma. Remove the skillet from the heat and set the mixture aside.
4. Whisk the Custard Base: In a large mixing bowl, beat the six large eggs until they are well combined and slightly frothy. Gradually whisk in the milk, heavy whipping cream, Dijon mustard, ½ teaspoon of kosher salt, and a generous pinch of freshly ground black pepper. Whisk vigorously until all ingredients are thoroughly incorporated and smooth. This is your flavorful custard.
5. Add the Spinach: Stir the thoroughly squeezed and cooked baby spinach into the egg custard mixture. Ensure the spinach is evenly distributed throughout the liquid. Remember, squeezing out excess water from the spinach is vital to prevent a soggy casserole.
6. Arrange the Croissants: Take your mini croissants (or quartered large croissants) and arrange them in a single layer in the prepared baking dish. Place them on an angle, slightly overlapping, to create a stable base and allow maximum surface area for soaking. They don’t need to be perfectly neat, but aim for even coverage.
7. Layer with Ham and Onion: Evenly sprinkle the sautéed ham and onion mixture over the layer of croissants in the baking dish. Make sure every piece of croissant has some of the savory topping for consistent flavor.
8. Pour the Custard: Carefully pour the egg and spinach mixture over the croissants and ham. Gently press down on the croissants with a spatula if needed, ensuring they are fully submerged and soak up the delicious liquid. This is key to achieving that wonderfully soft, custardy texture.
9. Top with Cheese: Generously sprinkle the shredded Gruyere cheese (or your cheese of choice) over the entire casserole. The cheese will melt into a golden, bubbly crust during baking, adding incredible flavor and texture.
10. Overnight Soak (The Magic Step): Cover the baking dish tightly with aluminum foil or plastic wrap. Place it in the refrigerator and allow it to chill overnight, or for a minimum of 8 hours. This extended resting period allows the croissants to thoroughly absorb the liquid, transforming them into a soft, bread pudding-like consistency rather than just soggy bread. This step is critical for the casserole’s success.
11. Bake to Perfection: The next morning, preheat your oven to 375°F (190°C). Place the covered casserole in the preheated oven and bake for 40 minutes. After this time, carefully remove the foil and continue baking for an additional 15-20 minutes, or until the casserole is golden brown on top, puffed, and the egg custard has set firmly in the middle (a knife inserted into the center should come out clean).
12. Serve and Enjoy: Once baked, remove the casserole from the oven and let it rest for 5-10 minutes before slicing and serving. This allows the casserole to set further and makes for cleaner slices. Garnish with fresh green onions, if desired, and prepare for rave reviews!

Chef Jenn’s Expert Tips for the Perfect Casserole

• Croissant Size Matters: If you’re using larger, standard-sized croissants instead of mini ones, be sure to cut them into quarters. This ensures a more even distribution of the buttery pastry and allows for better absorption of the egg custard, preventing any dry spots and ensuring every bite is moist and flavorful.
• Boost Your Veggies: Don’t hesitate to get creative with additional vegetables. Sautéed mushrooms, finely diced bell peppers (any color), or even a handful of sun-dried tomatoes can add fantastic layers of flavor, texture, and visual appeal to your casserole. Just make sure to pre-cook any harder vegetables to ensure they soften properly during the bake.
• Cheese Choices: While Gruyere is a personal favorite for its rich, nutty profile and excellent melting qualities, this recipe is highly adaptable to other cheeses. Feel free to use any easy-melting cheese you prefer or have on hand. Excellent alternatives include sharp cheddar, creamy Monterey Jack, Fontina, or even a blend of Italian cheeses. Experiment to find your perfect cheesy combination!
• Maximizing Absorption: For the best results, ensure your croissants are at least a day old, or slightly stale. Stale bread products absorb liquids much more effectively than fresh ones, preventing the casserole from becoming soggy while ensuring a custardy interior.
• Prevent Browning: If you notice the top of your casserole browning too quickly before the center is set, simply tent it loosely with aluminum foil. This protects the crust from over-browning while allowing the inside to continue cooking evenly.
• Check for Doneness: To ensure the egg custard is fully cooked, insert a knife into the center of the casserole. If it comes out clean, your casserole is ready. The edges should be beautifully golden and slightly puffed.

More Delicious Breakfast Casserole Inspirations

Make It A Complete Brunch Experience

While this Croissant Breakfast Casserole is certainly a showstopper on its own, you can elevate your brunch spread by pairing it with complementary dishes and beverages. For a balanced meal, consider serving it alongside a vibrant fruit salad featuring seasonal berries, melon, and citrus segments. Add a refreshing crunch with a side of freshly baked muffins or crispy bacon. Don’t forget the drinks – a large pot of freshly brewed coffee is a must, and for a celebratory touch, a pitcher of sparkling mimosas or a festive cranberry punch would be perfect additions to wash it all down.

Storage and Reheating Made Easy

One of the many advantages of this breakfast casserole is how well it stores, allowing you to enjoy leftovers for days or prepare it far in advance. To store any remaining portions, first allow the casserole to cool completely to room temperature. Once cooled, cover the baking dish tightly with aluminum foil or transfer individual slices to airtight containers. It can then be refrigerated for up to 3 days, maintaining its delicious flavor and texture.

For reheating, you have a couple of convenient options. To reheat larger portions or the entire casserole, place it back in the oven at 350°F (175°C) until warmed through, usually about 15-20 minutes for a covered dish. For individual servings, the microwave works wonderfully: simply heat at 30-second intervals until hot. Be careful not to overcook, as this can dry out the croissants and eggs.

If you wish to extend its life even further, this casserole freezes beautifully. Wrap the cooled casserole tightly with several layers of plastic wrap and then aluminum foil, or place it in a freezer-safe container. It can be frozen for up to 2 months. When ready to enjoy, thaw the frozen casserole overnight in the refrigerator before reheating as directed above. This versatility makes it ideal for meal prep or for having a delicious breakfast ready on demand.

Croissant Breakfast Casserole Recipe Card

Rich, creamy, and loaded with spinach, ham, and cheese, this Breakfast Croissant Casserole is packed with flavor and is an effortless choice for breakfast or brunch, perfect for any occasion.

Course: Breakfast, Brunch

Cuisine: American

Keywords: breakfast, breakfast casserole, croissant, ham, cheese, make-ahead

Prep Time: 15 minutes

Cook Time: 1 hour

Servings: 8 servings

Author: Chef Jenn

Ingredients

• 15 mini croissants (cut in half, or 8 large croissants cut into quarters)
• 1 cup diced sweet onion
• 10 ounces diced ham
• 6 large eggs
• 1 cup milk
• 1 cup heavy whipping cream
• 2 tablespoons Dijon mustard
• ½ teaspoon salt
• Freshly ground black pepper, to taste
• ½ cup cooked baby spinach (squeezed dry, about 8 ounces fresh)
• 6 ounces shredded Gruyere cheese
• Cooking oil or butter (for sautéing)
• Nonstick cooking spray

Instructions

1. Spray a 9×13-inch baking dish with nonstick cooking spray and set it aside.
2. Heat a skillet over medium heat. Add the oil or butter, then sauté the onions until they become translucent (about 5-7 minutes).
3. Add the diced ham to the skillet and cook for another 2-3 minutes, stirring to combine. Set aside.
4. In a large bowl, beat the eggs. Whisk in the milk, heavy whipping cream, Dijon mustard, kosher salt, and pepper until well combined.
5. Stir the squeezed-dry spinach into the egg mixture, ensuring it’s evenly distributed.
6. Arrange the mini croissants (or quartered large croissants) in the prepared baking dish, placing them on an angle so they slightly overlap.
7. Evenly sprinkle the ham and onion mixture over the top of the croissants.
8. Pour the egg and spinach mixture over the croissants, gently pressing down to ensure the liquid is absorbed all around the croissants.
9. Top generously with shredded Gruyere cheese.
10. Cover the dish with foil or plastic wrap and refrigerate overnight, or for at least 8 hours, allowing the liquid to fully soak into the croissants.
11. The next morning, preheat your oven to 375°F (190°C). Bake the covered casserole for 40 minutes.
12. Remove the foil and continue to bake for an additional 15-20 minutes, or until the casserole is golden brown and the egg has fully set in the middle (a knife inserted should come out clean).
13. Remove from oven, let rest for 5-10 minutes, then slice and serve warm. Enjoy your delicious Croissant Breakfast Casserole!

Notes

Chef Jenn’s Tips

• If using large croissants, cut them into quarters before adding them to the baking dish for better absorption and serving.
• Feel free to add other vegetables, like sautéed mushrooms, bell peppers, or even sun-dried tomatoes for extra flavor and color.
• Gruyere is a fantastic choice for this breakfast casserole, but you can substitute any easy-melting cheese. Mozzarella, sharp cheddar, Monterey Jack, and Fontina are all delicious options.
• For the best texture, use day-old or slightly stale croissants, as they absorb the egg custard more effectively without becoming overly soft.

Nutrition

A Note on Nutritional Information

Nutritional information for this recipe is provided as a courtesy and is calculated based on available online ingredient information. It is only an approximate value. The accuracy of the nutritional information for any recipe on this site cannot be guaranteed.