Save The smell of nutmeg and butter hit me the moment I opened my friend's oven door, and I knew I had to learn what she was making. She pulled out this golden, bubbling casserole and called it a lazy Croque Monsieur. I'd only ever had the sandwich pressed between a panini maker at a café, but this baked version felt like something I could actually pull off on a Sunday morning. We ate it straight from the dish with forks, laughing at how indulgent it was. I went home that day with her scribbled recipe on a napkin.
I made this for my sister's birthday brunch last spring, and it disappeared faster than I expected. She kept saying it reminded her of the breakfast we had in Paris years ago, except better because we were eating it in pajamas. My brother-in-law, who usually avoids anything with cream sauce, went back for seconds. I realized then that this casserole had a way of making people feel taken care of without me having to do much at all.
Ingredients
- White sandwich bread: Use soft, fresh bread and remove the crusts so it soaks up the custard evenly without getting tough or chewy.
- Unsalted butter: Buttering each slice before layering adds richness and helps the top turn golden and crisp in the oven.
- Gruyère cheese: This is the traditional choice for Croque Monsieur because it melts beautifully and has a nutty, slightly sweet flavor that balances the saltiness of the ham.
- Whole milk and heavy cream: Together they create a custard that is rich but not overwhelming, binding everything into a cohesive, creamy casserole.
- Eggs: They give structure to the custard and help the bread puff up as it bakes.
- Cooked ham: Deli ham works perfectly here, but you can also use leftover holiday ham or even turkey if that is what you have.
- All-purpose flour: This thickens the béchamel sauce so it coats the casserole instead of pooling at the bottom.
- Ground nutmeg: Just a pinch brings warmth and depth to the béchamel without making it taste like dessert.
- Salt and black pepper: Season every layer lightly so the flavors build without any one bite tasting flat.
Instructions
- Preheat and Prep Your Dish:
- Set your oven to 375°F and butter a 9x13-inch baking dish generously so nothing sticks. This step also warms up your kitchen and gets you in the cooking mood.
- Make the Béchamel Sauce:
- Melt 2 tablespoons of butter in a saucepan over medium heat, whisk in the flour, and let it cook for a minute until it smells toasty. Slowly pour in the milk while whisking constantly until the sauce thickens and coats the back of a spoon, then season it with nutmeg, salt, and pepper before setting it aside.
- Butter the Bread:
- Spread softened butter on one side of each slice of bread. This might feel fussy, but it makes all the difference in texture and flavor.
- Layer the Casserole:
- Arrange half the bread slices buttered side down in the dish, then layer on half the ham and half the Gruyère. Repeat with the remaining bread, ham, and cheese so every bite has balance.
- 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 down gently so the bread absorbs the liquid. Let it sit for a minute or two if you have time.
- Add the Béchamel:
- Pour the béchamel sauce over the top and spread it evenly with a spatula. It will look like a lot, but it soaks in as it bakes.
- Bake Until Golden:
- Slide the dish into the oven uncovered and bake for 35 to 40 minutes until the top is puffed, golden, and bubbling around the edges. Let it rest for 10 minutes before serving so it sets up and does not fall apart when you scoop it.
Save One morning I served this to a friend who had just moved and was living out of boxes. She sat at my table with a huge portion and said it felt like the first real meal she'd had in weeks. We talked for hours while the empty dish sat between us. That is when I understood that some recipes are not just about feeding people, they are about giving them a moment to slow down and feel at home.
Make It Your Own
I have made this casserole vegetarian by leaving out the ham and adding sautéed mushrooms and spinach between the layers. It was just as satisfying and honestly a little lighter. You can also spread a thin layer of Dijon mustard on the buttered bread for a sharper, more traditional Croque Monsieur flavor. My neighbor swears by adding a handful of caramelized onions, and I have to admit it works beautifully.
Serving Suggestions
This casserole is rich, so I always serve it with something fresh and bright to balance it out. A simple green salad with lemon vinaigrette or a handful of arugula on the side cuts through the cream and cheese perfectly. If you are serving it for brunch, a glass of chilled Chardonnay or a sparkling mimosa makes it feel a little more special. Leftovers reheat surprisingly well in the oven, though they never last long in my house.
Storage and Timing
You can assemble this casserole the night before, cover it tightly with plastic wrap, and refrigerate it until you are ready to bake. Just add an extra 5 to 10 minutes to the baking time if it is going in cold. Leftovers keep in the fridge for up to three days and reheat beautifully in a 350°F oven until warmed through.
- Assemble up to 24 hours ahead and bake fresh for stress free entertaining.
- Reheat individual portions in the oven at 350°F for about 15 minutes covered with foil.
- Freeze unbaked casserole tightly wrapped for up to a month and thaw overnight before baking.
Save This casserole has become my go to whenever I want to make something that feels generous without a lot of fuss. It fills the kitchen with warmth and makes everyone gather around the table a little longer than usual.
Recipe FAQs
- → Can I prepare this casserole ahead of time?
Yes, assemble the casserole up to 24 hours in advance, cover tightly, and refrigerate. Pour the béchamel sauce just before baking and add 5-10 minutes to the baking time if placing it cold in the oven.
- → What bread works best for this dish?
White sandwich bread is traditional, but brioche or sourdough adds extra flavor and richness. Remove crusts for a softer texture or leave them on for more structure.
- → Can I substitute the Gruyère cheese?
Swiss cheese is the closest substitute, offering similar nutty, melty qualities. Emmental or Comté also work well, while sharp cheddar provides a bolder flavor profile.
- → How do I make this vegetarian?
Omit the ham and add sautéed mushrooms, caramelized onions, or wilted spinach between the bread layers. The béchamel and cheese provide plenty of savory richness.
- → Why is my casserole soggy?
Ensure bread is properly buttered to create a barrier against moisture. Don't oversoak the bread in the custard mixture, and let the casserole rest 10 minutes after baking to set properly.
- → What should I serve with this casserole?
A crisp green salad with Dijon vinaigrette balances the richness perfectly. Roasted asparagus, fresh fruit, or a light soup also complement this indulgent dish beautifully.