Simple Ham and Cheese Croissant Breakfast Casserole

There’s something about croissants that makes breakfast feel special. Maybe it’s all those buttery layers or the way they seem fancy without trying too hard. Whatever it is, I’ve found a way to turn them into a breakfast casserole that feeds a crowd without making you feel like you need a culinary degree.

This ham and cheese croissant breakfast casserole is what I make when I want to impress without the stress. You can put it together the night before, stick it in the fridge, and pop it in the oven while you’re making coffee. The croissants soak up this creamy egg mixture overnight, the swiss cheese gets all melty, and that little bit of dijon mustard? It gives everything just enough flavor without being in your face about it.

I usually make this for weekend brunch or when we have family staying over. It looks like you spent hours in the kitchen, but really, you just tore up some croissants and whisked a few things together. That’s my kind of cooking.

What Kind of Croissants Should I Use?

You can use fresh bakery croissants or the ones from your grocery store’s bakery section – both work great for this casserole. Day-old croissants are actually perfect here since they’re a bit drier and will soak up the egg mixture better without getting too soggy. If you only have fresh croissants, you can leave them out on the counter for a few hours or even toast them lightly before assembling the casserole. Store-bought croissants from the refrigerated section will work in a pinch, though they won’t have quite the same buttery flavor as bakery-fresh ones.

Options for Substitutions

This breakfast casserole is pretty forgiving when it comes to swaps:

• Croissants: While croissants give this casserole its buttery richness, you can use day-old French bread, brioche, or even challah if that’s what you have. Cut them into similar-sized pieces so they soak up the egg mixture evenly.
• Half and half: You can use whole milk for a lighter version, or mix equal parts milk and heavy cream if you don’t have half and half on hand.
• Ham: Turkey, cooked bacon, or cooked sausage all work great here. You could also go meatless and add sautéed mushrooms or spinach instead.
• Swiss cheese: Gruyere is a classic swap that adds a nutty flavor, but cheddar, gouda, or monterey jack will work just fine too. Use whatever melts well and tastes good to you.
• Dijon mustard: Regular yellow mustard works in a pinch, though you might want to use a bit less since it’s sharper. Whole grain mustard is another tasty option.

Watch Out for These Mistakes While Baking

The biggest mistake with this casserole is cutting your croissants too small – aim for 2-inch pieces so they hold their shape and don’t turn mushy, and make sure to tear them by hand rather than using a knife to create uneven edges that soak up the custard better.

Don’t skip the 30-minute chilling time (or go overnight if you can), as this step is crucial for the croissants to fully absorb the egg mixture without becoming soggy on top and dry on the bottom.

When it comes to the cheese, avoid pre-shredded swiss since it contains anti-caking agents that prevent smooth melting – buy a block and shred it yourself for a creamier result.

Finally, resist the urge to skip covering the dish during the first 20 minutes of baking, as this traps steam and helps the casserole cook evenly without drying out the top layer of croissants.

What to Serve With Ham and Cheese Croissant Breakfast Casserole?

This casserole is pretty filling on its own, so I like to keep the sides simple and fresh. A fruit salad with berries, melon, and grapes is always a hit at brunch and helps balance out the richness of the croissants and cheese. You could also serve it with a light arugula salad tossed with lemon juice and olive oil, or some roasted asparagus on the side. If you’re feeding a crowd for breakfast or brunch, consider adding some crispy bacon strips or breakfast sausage links for the meat lovers at your table.

Storage Instructions

Store: This casserole keeps really well in the fridge for up to 4 days. Just cover it tightly with plastic wrap or transfer it to an airtight container. It makes a great make-ahead breakfast for busy mornings!

Make Ahead: You can actually assemble this whole casserole the night before and let it sit in the fridge overnight. The croissants will soak up all that eggy goodness while you sleep, and in the morning you just pop it in the oven. Super convenient for holiday mornings or when you have guests.

Reheat: Warm up individual portions in the microwave for about 60-90 seconds, or reheat the whole thing covered with foil in a 350°F oven for about 15-20 minutes. Add a fresh dusting of powdered sugar right before serving to make it look pretty again.

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 2950-3200
• Protein: 100-115 g
• Fat: 170-190 g
• Carbohydrates: 215-240 g

Ingredients

For the casserole:

• 9 croissants (torn into 1-inch pieces and toasted slightly)
• 9 oz ham (diced into 1/2-inch cubes)
• 7 oz swiss (I recommend Boar’s Head for the sharpest flavor)
• 4 large eggs (at room temperature)
• 1 cup half and half
• 1.5 tbsp dijon mustard (I prefer Maille for more depth)
• 3/4 tsp salt
• 1/4 tsp black pepper

For the garnish:

• 2 tbsp powdered sugar

Step 1: Prepare the Croissants and Assemble the Base

• 9 croissants
• 9 oz ham
• 7 oz Swiss cheese
• butter or cooking spray for greasing

Tear the croissants into 1-inch pieces and spread them on a baking sheet.

Toast them in a 350°F oven for about 5-7 minutes, stirring halfway through, until they’re lightly golden and slightly dried out—this prevents them from becoming soggy in the custard.

While the croissants toast, grease a 9×13 inch baking dish with butter or cooking spray, then dice the ham into 1/2-inch cubes and shred the Swiss cheese.

Once the croissants have cooled slightly, transfer them to the prepared baking dish and scatter the diced ham and shredded cheese evenly throughout.

Step 2: Make the Custard Mixture

• 4 large eggs
• 1 cup half and half
• 1.5 tbsp dijon mustard
• 3/4 tsp salt
• 1/4 tsp black pepper

In a medium bowl, whisk together the eggs, half and half, Dijon mustard, salt, and black pepper until completely smooth and well combined.

I like using Dijon mustard here because it adds a subtle savory depth that complements the ham without overpowering the delicate cheese and croissant flavors.

Make sure the eggs are well incorporated to create an even custard that will cook uniformly.

Step 3: Combine and Chill the Casserole

• croissant and ham mixture from Step 1
• custard mixture from Step 2

Pour the custard mixture from Step 2 evenly over the croissant, ham, and cheese mixture in the baking dish from Step 1.

Gently stir with a fork to ensure the custard distributes throughout and all the croissant pieces are moistened.

Cover the dish tightly with plastic wrap or aluminum foil and refrigerate for at least 30 minutes—this allows the croissants to absorb the custard and helps the flavors meld together for a more cohesive dish.

Step 4: Bake the Casserole Covered, Then Finish Uncovered

• assembled casserole from Step 3

Preheat your oven to 350°F and place the chilled casserole (still covered) on the middle rack.

Bake for 20 minutes covered to gently cook the eggs and warm the filling without drying it out.

Then uncover the dish and bake for an additional 10-15 minutes until the top is golden brown and a knife inserted in the center comes out clean.

I find that baking covered first prevents the top from browning too quickly while the center finishes cooking.

Step 5: Rest and Serve with Powdered Sugar

• baked casserole from Step 4
• 2 tbsp powdered sugar

Remove the casserole from the oven and let it rest for 5 minutes before serving—this allows the custard to set completely and makes it easier to cut clean portions.

Dust the top generously with powdered sugar just before serving for a subtle sweetness that balances the savory ham and cheese.

Serve warm directly from the dish or cut into squares for individual portions.

Simple Ham and Cheese Croissant Breakfast Casserole

Delicious Simple Ham and Cheese Croissant Breakfast Casserole recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 30 minutes mins

Total Time 45 minutes mins

Servings 8 servings

Calories 3075 kcal

Ingredients

  

For the casserole::

• 9 croissants (torn into 1-inch pieces and toasted slightly)
• 9 oz ham (diced into 1/2-inch cubes)
• 7 oz swiss (I recommend Boar's Head for the sharpest flavor)
• 4 large eggs (at room temperature)
• 1 cup half and half
• 1.5 tbsp dijon mustard (I prefer Maille for more depth)
• 3/4 tsp salt
• 1/4 tsp black pepper

For the garnish::

• 2 tbsp powdered sugar

Instructions

 

• Tear the croissants into 1-inch pieces and spread them on a baking sheet. Toast them in a 350°F oven for about 5-7 minutes, stirring halfway through, until they're lightly golden and slightly dried out—this prevents them from becoming soggy in the custard. While the croissants toast, grease a 9x13 inch baking dish with butter or cooking spray, then dice the ham into 1/2-inch cubes and shred the Swiss cheese. Once the croissants have cooled slightly, transfer them to the prepared baking dish and scatter the diced ham and shredded cheese evenly throughout.
• In a medium bowl, whisk together the eggs, half and half, Dijon mustard, salt, and black pepper until completely smooth and well combined. I like using Dijon mustard here because it adds a subtle savory depth that complements the ham without overpowering the delicate cheese and croissant flavors. Make sure the eggs are well incorporated to create an even custard that will cook uniformly.
• Pour the custard mixture from Step 2 evenly over the croissant, ham, and cheese mixture in the baking dish from Step 1. Gently stir with a fork to ensure the custard distributes throughout and all the croissant pieces are moistened. Cover the dish tightly with plastic wrap or aluminum foil and refrigerate for at least 30 minutes—this allows the croissants to absorb the custard and helps the flavors meld together for a more cohesive dish.
• Preheat your oven to 350°F and place the chilled casserole (still covered) on the middle rack. Bake for 20 minutes covered to gently cook the eggs and warm the filling without drying it out. Then uncover the dish and bake for an additional 10-15 minutes until the top is golden brown and a knife inserted in the center comes out clean. I find that baking covered first prevents the top from browning too quickly while the center finishes cooking.
• Remove the casserole from the oven and let it rest for 5 minutes before serving—this allows the custard to set completely and makes it easier to cut clean portions. Dust the top generously with powdered sugar just before serving for a subtle sweetness that balances the savory ham and cheese. Serve warm directly from the dish or cut into squares for individual portions.