Croque Monsieur Casserole

Featured in: Soft Warm Bakes & Savory Treats

This Croque Monsieur Casserole transforms the beloved French bistro sandwich into a show-stopping baked dish. Layers of buttered bread, savory ham, and nutty Gruyère cheese are bound together with a custard-like mixture and topped with velvety béchamel sauce. Baked until golden and bubbling, it emerges from the oven puffed and irresistible. Ready in just an hour with easy prep, this crowd-pleaser serves six and pairs beautifully with a crisp salad and white wine.

Updated on Fri, 30 Jan 2026 16:08:00 GMT
Golden, puffed Croque Monsieur Casserole fresh from the oven with bubbling Gruyère cheese. Save to Pinterest
Golden, puffed Croque Monsieur Casserole fresh from the oven with bubbling Gruyère cheese. | olivefrost.com

My neighbor brought this to a potluck once, and I stood by the dish fork in hand until I realized I'd eaten three servings without moving. It wasn't just the cheese or the ham, it was the way the custard soaked into the bread and turned crispy at the edges. I asked for the recipe right there, scribbled on a napkin. Now it's the thing I make when I want to feel fancy without actually trying that hard.

The first time I baked this for my family, my brother said it looked like bread pudding and refused to try it. Then he smelled it. He ended up eating straight from the pan with a spatula while I plated everyone else's portions. We still joke about it, but now he requests it every time he visits.

Ingredients

  • White sandwich bread: Use soft, sturdy bread that soaks up custard without falling apart, and remove the crusts so the texture stays smooth and even.
  • Unsalted butter: Softened butter spreads easily on bread and creates golden, crispy layers that contrast with the creamy interior.
  • Gruyere cheese: This nutty, melty cheese is the heart of the dish, but Swiss works if Gruyere is hard to find or too pricey.
  • Whole milk and heavy cream: The combination makes the custard rich and silky without being too heavy or too thin.
  • Eggs: They bind everything together and give the casserole structure as it bakes.
  • Cooked ham: Adds smoky, savory depth, but you can swap it for turkey or leave it out entirely if you go vegetarian.
  • All-purpose flour: Thickens the bechamel so it clings to the bread instead of pooling at the bottom.
  • Ground nutmeg: A tiny pinch warms up the bechamel and makes the whole dish smell like a cozy bistro.

Instructions

Product image
Wash produce, prep ingredients, rinse cookware, and streamline cooking tasks with an all-in-one sink workstation.
Check price on Amazon
Prep your dish:
Preheat the oven to 375°F and butter a 9x13 inch baking dish generously so nothing sticks. This step matters more than you think.
Make the bechamel:
Melt butter in a saucepan, whisk in flour, and cook for a minute until it smells toasty. Slowly add milk while whisking constantly until the sauce thickens and coats the back of a spoon, then season with nutmeg, salt, and pepper.
Butter the bread:
Spread softened butter on one side of each slice. It feels like extra work, but this is what makes the top layer golden and crisp.
Layer the casserole:
Place half the bread buttered side down in the dish, then add half the ham and half the cheese. Repeat with remaining bread, ham, and cheese, pressing gently as you go.
Pour the custard:
Whisk eggs, milk, cream, and a pinch of salt together, then pour evenly over the layers. Press down lightly so the bread soaks it up instead of floating.
Add the bechamel:
Pour the sauce over the top and spread it gently with a spatula. It will look like too much, but it melts into everything as it bakes.
Bake until golden:
Slide it into the oven uncovered and bake for 35 to 40 minutes until puffed, bubbling, and deeply golden on top. Let it rest for 10 minutes before cutting so it sets up and doesn't fall apart.
Product image
Wash produce, prep ingredients, rinse cookware, and streamline cooking tasks with an all-in-one sink workstation.
Check price on Amazon
Gooey, melted cheese topping on a savory Croque Monsieur Casserole ready to serve. Save to Pinterest
Gooey, melted cheese topping on a savory Croque Monsieur Casserole ready to serve. | olivefrost.com

One Sunday morning I made this and sat at the table with coffee and the paper while it baked. The smell filled the whole house, warm and buttery and just a little nutmeg sweet. My partner wandered in half asleep and said it smelled like a bakery. We ate it straight from the dish, still too hot, and didn't talk much. It's one of those meals that doesn't need conversation.

How to Prep Ahead

You can assemble the entire casserole the night before, cover it tightly with plastic wrap, and keep it in the fridge. In the morning, let it sit at room temperature for 20 minutes while the oven heats, then bake as directed. The bread soaks up even more custard overnight, which makes the texture even better. Just add a few extra minutes to the baking time if it goes in cold.

Best Ways to Serve It

This casserole is rich, so balance it with something bright and crisp like a simple green salad with lemon vinaigrette or lightly dressed arugula. A glass of chilled Chardonnay or a sparkling water with lemon feels right alongside it. If you're serving it for brunch, fresh fruit or roasted tomatoes on the side cut through the richness without competing for attention.

Storage and Reheating

Leftovers keep covered in the fridge for up to three days and reheat beautifully in a 350°F oven for about 15 minutes. You can also microwave individual portions, but the oven brings back that crispy top. It's one of those rare dishes that tastes just as good the next day, maybe even better once all the flavors settle in.

  • Cover leftovers tightly so they don't dry out in the fridge.
  • Reheat in the oven instead of the microwave if you want to keep the top crispy.
  • Freeze individual portions wrapped well for up to a month and bake from frozen at 350°F for 25 minutes.
Product image
Quickly chop vegetables, blend sauces, and prepare dips or dressings for fast, everyday meal prep.
Check price on Amazon
Sliced Croque Monsieur Casserole revealing layers of ham, bread, and creamy béchamel sauce. Save to Pinterest
Sliced Croque Monsieur Casserole revealing layers of ham, bread, and creamy béchamel sauce. | olivefrost.com

This casserole has become my go to when I want something that feels special but doesn't demand much from me. It's comfort and elegance in the same dish, and it never lets me down.

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 starting from cold.

What cheese works best if I can't find Gruyère?

Swiss cheese is the closest substitute with a similar nutty, mild flavor. Emmental, Comté, or a sharp white cheddar also work well. Avoid pre-shredded cheese for the best melting quality.

How do I make this vegetarian?

Simply omit the ham and add sautéed mushrooms, caramelized onions, or wilted spinach between the bread layers. The béchamel and cheese provide plenty of richness and flavor.

Why remove the crusts from the bread?

Removing crusts creates a more refined texture and allows the bread to absorb the egg mixture more evenly. It also gives the casserole a smoother, more elegant appearance when baked.

Can I use a different type of bread?

White sandwich bread works best for its soft texture, but brioche or challah adds extra richness. Sourdough provides a tangier flavor. Avoid very dense or seeded breads that won't absorb the custard well.

What should I serve alongside this casserole?

A simple green salad with vinaigrette balances the richness perfectly. Roasted asparagus, sautéed green beans, or fresh fruit also complement the dish beautifully for brunch or dinner.

Croque Monsieur Casserole

French-inspired casserole with buttery bread, ham, Gruyère, and creamy béchamel sauce. Perfect for any meal.

Prep Time
20 minutes
Time to Cook
40 minutes
Overall Duration
60 minutes
Recipe by Natalie Wilson


Skill Level Easy

Cuisine Type French

Serves 6 Portions

Dietary Info None specified

What You Need

Bread & Dairy

01 12 slices white sandwich bread, crusts removed
02 4 tablespoons unsalted butter, softened
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

How-To Steps

Step 01

Prepare Oven and Baking Dish: 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

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

Step 04

Add Filling Layers: Top bread with half the ham slices and half the Gruyère cheese. Repeat layering with remaining bread, buttered side down, followed by remaining ham and cheese.

Step 05

Prepare Custard Mixture: Whisk together eggs, 1 cup milk, cream, and a pinch of salt in a bowl. Pour evenly over the casserole, pressing gently to allow the bread to absorb the liquid.

Step 06

Add Béchamel Topping: Pour prepared béchamel sauce over the top 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. Allow to rest for 10 minutes before serving.

What You'll Need

  • 9x13-inch rectangular baking dish
  • Medium saucepan
  • Wire whisk
  • Mixing bowls
  • Serrated bread knife

Allergy Details

Be sure to check ingredients for allergens and ask your doctor if you’re not sure.
  • Contains wheat gluten
  • Contains milk and dairy products
  • Contains eggs
  • Contains pork

Nutrition Details (per portion)

Intended only for informational use, not medical advice.
  • Calories: 420
  • Fats: 25 g
  • Carbohydrates: 28 g
  • Proteins: 21 g