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Perfect for a holiday brunch or a long weekend, this Croque Monsieur Breakfast Casserole is simple to throw together but packed with savory flavors that are sure to satisfy!
When serving brunch for a crowd, I love having an egg-based dish as my centerpiece. While a quiche is always a great option, this casserole is my new showstopper! Creamy, herby, and oh-so savory — and not to mention you don’t need to go through the effort of making pie crust from scratch.
For this recipe, I use day-old croissants, which almost give this casserole bread pudding vibes. It’s inspired by a Croque Monsieur sandwich, which is basically the French version of a basic ham and cheese sandwich. This casserole features chopped black forest ham, Gruyère cheese, Parmesan, thyme, and Dijon mustard, which gives you all the same flavors of the bistro staple but in a brunch-friendly format. The end result has crispy edges, a tender center, and bubbly cheese.
Ingredients:
- Unsalted Butter
- Day-Old Croissants
- Black Forest Ham
- Gruyère Cheese
- Large Eggs
- Whole Milk
- Whole Milk Greek Yogurt
- Kosher Salt
- Freshly Ground Black Pepper
- Garlic Powder
- Dijon Mustard
- Fresh Thyme
- Parmesan Cheese
Step-by-Step:
Step One: Prepare the Oven and Baking Dish
Position one oven rack in the middle and one near the top of the oven. Preheat the oven to 375°F. Grease a 9×13-inch baking dish with butter.
Step Two: layer the Croissants, Ham, and Cheese
Arrange the torn croissants in a single layer in the prepared baking dish. Add the ham and 1 cup of Gruyère cheese, evenly distributing both over the croissants.
Step Three: Make the Egg Mixture
In a medium bowl, whisk together the melted butter, eggs, milk, yogurt, salt, pepper, garlic powder, Dijon, and fresh thyme until well combined.
Step Four: Add Egg Mixture to Baking Dish
Carefully pour the egg mixture into the baking dish, ensuring all croissant pieces are evenly coated. Sprinkle evenly with the remaining 1/2 cup Gruyère and Parmesan cheese.
Step Five: Bake
Transfer to the oven on the middle rack and bake for 30 minutes. After 30 minutes, move the casserole to the higher rack and bake for an additional 15 to 20 minutes, or until the top is a deep, golden brown and the center is set.
Step Six: Cool and serve
Allow to cool for 10 to 15 minutes. Garnish with the remaining thyme and cut into 8 squares. Enjoy!
Recipe FAQs:
Day old croissants are recommended because they dry out enough that they don’t get soggy. The best way to dry them out quickly is to leave them out out on the counter, uncovered, overnight. If you don’t have time to prep ahead, you can bake the croissants in a 375°F oven for about 10 minutes until they’re no longer soft.
This is a great way to use leftover holiday ham! Simply swap in 1 to 2 cups of diced ham in place of the deli ham.
Yes! If you have a large brunch spread with other items, you can definitely cut this into smaller pieces and serve about 12 people.
I hope you enjoy this Croque Monsieur Breakfast Casserole for your upcoming Easter celebration or any brunch plans you have! Comment below once you make this!
want More brunch-friendly Recipes? try these!
Italian Sausage and Arugula Quiche
Old Fashioned Breakfast Casserole
Croque Monsieur Breakfast Casserole
Ingredients
- 4 tablespoons unsalted butter, melted and cooled, plus more for greasing
- 5 cups torn day-old croissant cubes, about 2 inches (from 3 to 4 large croissants)
- 1/2 pound thinly sliced black forest ham, roughly chopped
- 1½ cups shredded Gruyère cheese, divided
- 8 large eggs
- 1½ cups whole milk
- 1/2 cup whole milk Greek yogurt
- 1 teaspoon kosher salt
- 1 teaspoon freshly ground black pepper
- 1 teaspoon garlic powder
- 1 tablespoon Dijon mustard
- 1 tablespoon roughly fresh thyme leaves, plus more for garnish
- 1/2 cup grated Parmesan cheese
Instructions
- Position one oven rack in the middle and one near the top of the oven. Preheat the oven to 375°F. Grease a 9×13-inch baking dish with butter.
- Arrange the torn croissants in a single layer in the prepared baking dish. Add the ham and 1 cup of Gruyère cheese, evenly distributing both over the croissants.
- In a medium bowl, whisk together the melted butter, eggs, milk, yogurt, salt, pepper, garlic powder, Dijon, and fresh thyme until well combined.
- Carefully pour the egg mixture into the baking dish, ensuring all croissant pieces are evenly coated. Sprinkle evenly with the remaining 1/2 cup Gruyère and Parmesan cheese.
- Transfer to the oven on the middle rack and bake for 30 minutes. After 30 minutes, move the casserole to the higher rack and bake for an additional 15 to 20 minutes, or until the top is a deep, golden brown and the center is set.
- Allow to cool for 10 to 15 minutes. Garnish with the remaining thyme and cut into 8 squares. Enjoy!
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
Photography and styling by Eat Love Eats.
Delicious and easy and made the house smell amazing!
Glad to hear it! This has become a big favorite of mine!
LOved this one! I followed the recipe to the letter EXCEPT I had to omit the dijon mustard because one of my guests is a mustard hater. It was still delicious. Used Costco croissants (3 of the big ones) and Costco gruyere cheese. DOn’t skimp on the fresh thyme! TO speed things up this morning, I prepped some items last night ( tore up the croissants, shredded both cheese and picked the thyme leaves. I love that I could make this the morning of our Easter brunch. It puffs up spectacularly in the oven but then collapses on itself leaving a rich dense casserole. My salt was Morton’s Kosher and it’s definitely a salty savoury dish so if you have salt-phobics or nutritionists at your table you may want to cut back. Served it with roasted asparagus, tomatoes and pine nuts and a fresh fruit platter. I will definitely make this one again. Thank you!
Fantastic!!! thank you for sharing your feedback, cindy!
I love all the specific details you provided! What brand ham did you use?
I will usually use black forest ham from the deli counter, cut a little thicker- but I use honey baked ham!
So yummy and easy! Made my Easter brunch and big hit for the kids 🥰
yay!! happy to hear you all loved it, too!
This was so delicious!! The perfect special occasion breakfast that came together quickly. Made it for Easter breakfast and the whole family loved it.
Wonderful, Maggie! Thank you!
I see others have asked about making it the night before and it’s not recommended but doable that’s my gathering however I just wanted to add another change and that is for your your critique I have used smoked turkey rather than ham as my daughter will not eat pork.
I’m wondering if I could make this tonight and refrigerate the whole mixture taking it out the next morning to bake it…??!
This turned out to be an excellent breakfast, which I cut in half. I followed the recipe at every ingredient and direction. except for the croissants – I only had one. so, in addition to the one croissant, I used two slightly sweet bread rolls that I had left over from a local bakery. What a great recipe!
Glad you enjoyed this and that the swap to sweet rolls worked!
How would you recommend storing/reheating this?
To Store: Let the bake cool completely, then cover and refrigerate for up to 3 days.
To Reheat: Warm individual portions in the oven at 350°F for about 10 minutes or until heated through. You can also microwave a slice for about 1–2 minutes, but the oven helps keep the texture crisp and fluffy.
The article says this serves 8 but then the recipe serving size shows 6. Recognizing it really just depends on how it is cut, does this really satisfy 8 as a meal or is it better to serve for 6?
Apologies — that was a typo! This definitely serves 8.
Can this be made the night before?
Can this be made and frozen or made a day ahead and baked within 24-48 hours? Sogginess worries me…!
While it’s not as good baked immediately- you can Yes! You can assemble the Croque Monsieur Breakfast Bake up to 24 hours in advance—just cover tightly and refrigerate until ready to bake. Make sure your croissants are pretty stale for this.
If you want to freeze: but you can bake it, let it cool completely, and then freeze individual portions for later!