Croque Monsieur Casserole

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This Croque Monsieur Casserole transforms the beloved French bistro sandwich into an elegant baked dish. Buttery white bread is layered with slices of savory ham and nutty Gruyère cheese, then soaked in a rich custard mixture of eggs, milk, and cream. A classic béchamel sauce crowns the casserole before baking, creating a golden, bubbling masterpiece perfect for brunch gatherings or cozy dinners.

Updated on Fri, 30 Jan 2026 16:27:00 GMT
Golden-brown, puffed Croque Monsieur Casserole fresh from the oven with bubbly Gruyère cheese topping. Pin it
Golden-brown, puffed Croque Monsieur Casserole fresh from the oven with bubbly Gruyère cheese topping. | happyzitoune.com

My neighbor brought this to a potluck last spring, and I watched six people go back for seconds before I even got a plate. She called it fancy, but I could see it was just bread, ham, and cheese baked together until bubbly. I made it the next weekend with what I had in my fridge, and now it shows up at every family gathering whether I plan it or not.

The first time I made this for my kids, they called it pizza bread until they tasted the creamy sauce. My youngest asked if we could have it every Sunday, and honestly, I considered it. There is something about the smell of melting Gruyère and buttery bread that makes everyone wander into the kitchen asking when dinner will be ready.

Ingredients

  • White sandwich bread: Remove the crusts so the edges get soft and custardy instead of tough, and use day old bread if you have it because it soaks up the egg mixture without falling apart.
  • Unsalted butter: You will use this twice, once to butter the bread and again for the béchamel, so soften half of it ahead of time to make spreading easier.
  • Gruyère cheese: This is the star of the dish with its nutty, slightly sweet flavor, but Swiss cheese works in a pinch if you cannot find it or want to save a few dollars.
  • Whole milk and heavy cream: The combination makes the custard rich without being too heavy, and you need both for the right texture.
  • Eggs: These bind everything together and create that puffy, soufflé like top when baked.
  • Cooked ham: Use deli ham or leftover holiday ham, and if you want to skip the meat, sautéed mushrooms or spinach work beautifully.
  • Béchamel ingredients: Butter, flour, milk, nutmeg, salt, and pepper create the creamy white sauce that makes this feel like a true French bistro dish.

Instructions

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Preheat and prep your dish:
Set your oven to 375°F and butter a 9x13 inch baking dish generously so nothing sticks. This step takes thirty seconds but saves you from scrubbing later.
Make the béchamel sauce:
Melt 2 tablespoons of butter in a saucepan over medium heat, whisk in the flour, and cook for a minute until it smells toasty. Slowly pour in the milk while whisking constantly so no lumps form, then cook until it thickens enough to coat the back of a spoon, about three to four minutes, and season it with nutmeg, salt, and pepper before setting it aside.
Butter the bread:
Spread softened butter on one side of each bread slice, which seems fussy but makes the layers golden and crisp. Arrange half the slices buttered side down in the dish.
Layer the filling:
Add half the ham slices, then half the grated Gruyère, and repeat with the remaining bread, ham, and cheese. Press down gently so everything nestles together.
Pour the custard:
Whisk together the eggs, milk, cream, and a pinch of salt in a bowl, then pour it evenly over the casserole and press the bread down so it soaks up the liquid. Let it sit for a minute or two if you have time.
Add the béchamel and bake:
Pour the béchamel sauce over the top and spread it gently with a spoon. Bake uncovered for 35 to 40 minutes until the top is puffed, golden, and bubbling at the edges, then let it rest for 10 minutes before serving so it sets up and does not fall apart when you scoop it.
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Layers of buttery bread, savory ham, and creamy béchamel sauce inside a baking dish. Pin it
Layers of buttery bread, savory ham, and creamy béchamel sauce inside a baking dish. | happyzitoune.com

I brought this to a brunch potluck once, and someone asked if I went to culinary school. I laughed and told them it was just a fancy grilled cheese, but they did not believe me until I wrote down the recipe on a napkin. That is the magic of this dish, it tastes like effort but feels like comfort.

Make Ahead Magic

Assemble the entire casserole the night before, cover it tightly with plastic wrap, and refrigerate it until morning. Pull it out while the oven preheats, let it sit on the counter for fifteen minutes to take the chill off, then bake as directed. You might need to add five extra minutes to the baking time, but it will come out just as golden and bubbly.

Swap Ideas That Work

If you want to skip the ham, layer in sautéed mushrooms, caramelized onions, or wilted spinach for a vegetarian version that still feels indulgent. I have also used turkey, roast beef, and even leftover rotisserie chicken when that is what I had on hand. A thin layer of Dijon mustard between the bread and ham adds a sharp, tangy note that my husband swears makes the whole thing better.

Serving and Storing

Serve this with a simple green salad dressed in lemon vinaigrette to cut through the richness, and pour a crisp white wine if you are feeling fancy. Leftovers keep in the fridge for up to three days and reheat beautifully in a 350°F oven covered with foil, or you can microwave individual portions for a quick lunch.

  • Cover leftovers tightly so they do not dry out in the fridge.
  • Reheat in the oven instead of the microwave if you want the top to stay crispy.
  • Freeze individual portions wrapped in foil for up to a month and bake from frozen at 350°F for about 30 minutes.
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Serving slice of rich Croque Monsieur Casserole with fresh greens for a French-inspired dinner. Pin it
Serving slice of rich Croque Monsieur Casserole with fresh greens for a French-inspired dinner. | happyzitoune.com

This casserole has become my go to for mornings when I want something special without the fuss. It never fails to make people happy, and that is really all a recipe needs to do.

Recipe FAQs

Can I prepare this casserole ahead of time?

Yes, assemble the casserole up to 24 hours in advance, cover tightly with plastic wrap, and refrigerate. Add the béchamel sauce just before baking and allow an extra 5-10 minutes in the oven if baking from cold.

What's the best bread to use for this dish?

White sandwich bread works perfectly as it absorbs the custard mixture well. Brioche or challah can be used for a richer, more buttery flavor. Remove crusts for the most authentic texture.

Can I substitute the Gruyère cheese?

Swiss cheese is the closest substitute and works beautifully. Emmental, Comté, or even sharp white cheddar can be used, though they'll alter the traditional flavor profile slightly.

How do I make this vegetarian?

Omit the ham and add layers of sautéed mushrooms, caramelized onions, or wilted spinach. The béchamel and cheese provide plenty of richness and flavor without the meat.

Why is my casserole soggy?

Ensure you're not using too much custard mixture and allow the casserole to rest for 10 minutes after baking. This helps it set properly. Also, avoid over-soaking the bread before adding the béchamel layer.

What should I serve with this casserole?

A crisp green salad with vinaigrette balances the richness perfectly. Roasted asparagus, steamed green beans, or a light arugula salad also pair wonderfully with this dish.

Croque Monsieur Casserole

Buttery bread layers with ham, Gruyère, and creamy béchamel sauce baked until golden and bubbling.

Prep time
20 min
Cook time
40 min
Overall time
60 min
Created by Liam Fletcher


Skill level Easy

Cuisine French

Makes 6 Portions

Dietary details None specified

What You’ll Need

Bread & Dairy

01 12 slices white sandwich bread, crusts removed
02 2 tablespoons unsalted butter, softened, plus extra for greasing
03 1.5 cups Gruyère cheese, grated
04 1 cup whole milk
05 0.5 cup heavy cream
06 3 large eggs

Meats

01 8 slices cooked ham, approximately 7 ounces

Béchamel Sauce

01 2 tablespoons unsalted butter
02 2 tablespoons all-purpose flour
03 1.25 cups whole milk
04 0.25 teaspoon ground nutmeg
05 Salt and black pepper to taste

Directions

Step 01

Prepare Baking Dish and Oven: Preheat oven to 375°F. Lightly butter a 9x13-inch baking dish and set aside.

Step 02

Prepare Béchamel Sauce: In a medium saucepan, melt 2 tablespoons butter over medium heat. Whisk in flour and cook for 1 minute. Gradually whisk in 1.25 cups milk, stirring constantly, until thickened and smooth, approximately 3 to 4 minutes. Season with nutmeg, salt, and pepper. Remove from heat.

Step 03

Layer Bread Foundation: Butter one side of each bread slice. Arrange half the bread slices, buttered side down, in the prepared baking dish.

Step 04

Add Protein and Cheese: Top the bread layer with half the ham slices and half the Gruyère cheese. Repeat with remaining bread slices buttered side down, remaining ham, and remaining cheese.

Step 05

Prepare Custard Mixture: In a mixing bowl, whisk together eggs, 1 cup milk, cream, and a pinch of salt. Pour evenly over the casserole and press gently to ensure bread absorbs the liquid.

Step 06

Add Béchamel Topping: Pour the béchamel sauce over the casserole and spread evenly across the surface.

Step 07

Bake and Rest: Bake uncovered for 35 to 40 minutes until puffed, golden brown, and bubbling at the edges. Remove from oven and let rest for 10 minutes before serving.

Equipment needed

  • 9x13-inch baking dish
  • Medium saucepan
  • Whisk
  • Mixing bowls
  • Bread knife

Allergy notes

Double-check each ingredient for allergens, and speak with a healthcare professional if unsure.
  • Contains wheat gluten
  • Contains milk and dairy products
  • Contains eggs
  • Contains pork

Nutrition info (each serving)

Details here are for general knowledge and aren’t medical advice.
  • Calorie count: 420
  • Fat content: 25 g
  • Carbohydrates: 28 g
  • Proteins: 21 g