Save My neighbor Marie invited me over for Sunday brunch and served this casserole straight from her oven, steam rising off the golden top. She called it her secret weapon for feeding a crowd without spending hours in the kitchen, and watching everyone go back for thirds, I understood why. It's the croque monsieur you love, but transformed into something even more indulgent and shareable. The first bite melted on my tongue—crispy edges giving way to creamy, cheesy layers that tasted like a French bistro translated into comfort food.
I made this for my book club last month, and Sarah (the picky eater we always worry about) asked for the recipe before dessert was even served. That's when I knew it had passed the ultimate test. There's something about the combination of salty ham, nutty Gruyère, and that whisper of nutmeg in the sauce that just works—no pretension, no fussy techniques, just pure deliciousness.
Ingredients
- White sandwich bread, crusts removed: The crusts would turn tough in the oven, so removing them gives you tender, absorbent layers that soak up the custard without getting dense.
- Unsalted butter: You're controlling the salt here, so unsalted lets you season properly; softening it first makes spreading effortless.
- Gruyère cheese: Its nutty, slightly sweet flavor is what elevates this beyond a basic cheese casserole—Swiss works too, but Gruyère feels more French bistro.
- Whole milk and heavy cream: The cream adds richness to the custard layer, making each bite velvety and luxurious.
- Eggs: These bind everything together and create that custardy texture when baked, turning bread into pure comfort.
- Cooked ham: Use quality deli ham if you can; thin, delicate slices work better than thick chunks because they distribute flavor evenly.
- Béchamel sauce: This is your secret weapon—the flour-butter roux whisked smooth with milk creates a silky sauce that holds everything together and adds another layer of richness.
- Ground nutmeg: Just a whisper prevents the dish from feeling heavy; too much and it overpowers everything else.
Instructions
- Heat your oven and prepare the stage:
- Set your oven to 375°F and butter that 9x13-inch dish generously—you want it slippery so nothing sticks and you can serve clean portions.
- Make the béchamel sauce:
- Melt butter over medium heat, whisk in flour until it smells toasty (about a minute), then slowly add milk while whisking constantly so no lumps form. Watch it thicken before your eyes, about 3 to 4 minutes—it should coat the back of a spoon. Season gently with nutmeg, salt, and pepper, then set it aside to cool slightly.
- Butter and layer your bread:
- Spread softened butter on one side of each bread slice, then arrange half of them buttered side down in your dish—they should fit snugly in two layers.
- Build the middle layers:
- Scatter half your ham slices over the bread, then half the grated Gruyère, creating an even distribution so every bite has ham and cheese.
- Top with the second layer:
- Repeat with remaining bread (buttered side down), ham, and cheese, pressing gently so everything nestles together.
- Mix your custard:
- Whisk eggs with milk, heavy cream, and a pinch of salt until combined, then pour this mixture evenly over the whole casserole. Use your hands to gently press down so the bread absorbs the liquid—don't be shy here.
- Add the béchamel crown:
- Pour that silky béchamel over the top and spread it in an even layer, like you're frosting a cake.
- Bake until golden:
- Slide it into the oven for 35 to 40 minutes—you're looking for a puffed, golden top with custard bubbling around the edges. Let it rest 10 minutes before cutting so it sets up and holds together.
Save There's a moment when this casserole comes out of the oven and you watch it puff up like a soufflé, all golden and steaming, that you realize you've created something special. It's not just breakfast or dinner anymore—it's a gathering, a reason for people to linger at the table.
Making It Your Own
The beauty of this casserole is how adaptable it is without losing its soul. I've tried it with smoked turkey instead of ham on nights when I wanted something lighter, and the flavor profile still sang. The vegetarian version with sautéed mushrooms and fresh spinach is equally satisfying—the earthiness of the mushrooms echoes what ham would have brought, and nobody misses the meat.
The Dijon Moment
My first time making this, I spread a thin layer of Dijon mustard between the bread and ham because I remembered croque monsieurs always having that sharp kick. It was a small detail, but it transformed the dish from comfort food into something with character. Now I always do it, and people taste that mysterious depth and wonder what I did differently.
Serving and Pairing
This casserole deserves a crisp green salad alongside it—something acidic to cut through the richness and cleanse your palate between bites. A glass of Chardonnay feels right too, the buttery notes echoing what's on your plate. It's elegant enough for a dinner party but casual enough for Sunday brunch with your closest friends.
- Cut it into neat squares and serve immediately while it's still puffed and warm.
- Leftovers reheat gently in a 300°F oven, covered with foil so the top doesn't dry out.
- This is perfect make-ahead food—assemble it the night before, cover it, and bake it fresh in the morning.
Save This casserole has become my answer to the question every cook dreads: what do I make when I want to impress people without stress? It delivers every single time, golden and bubbling and absolutely foolproof.
Kitchen Guide
- → Can I make this casserole ahead of time?
Yes, assemble the casserole up to 24 hours in advance, cover with plastic wrap, and refrigerate. Add the béchamel sauce just before baking and increase baking time by 5-10 minutes if baking straight from the fridge.
- → What cheese can I use instead of Gruyère?
Swiss cheese is the closest substitute with a similar nutty flavor. Emmental, Comté, or even a sharp white cheddar work well. Avoid pre-shredded cheese for the best melting quality.
- → How do I prevent the casserole from becoming soggy?
Use slightly stale bread or lightly toast the slices before assembling. Press gently when pouring the egg mixture to ensure even soaking without oversaturating. Let it rest 10 minutes after baking to set properly.
- → Can I freeze leftovers?
Yes, portion cooled casserole into airtight containers and freeze for up to 2 months. Reheat individual portions in the oven at 350°F until warmed through, about 20-25 minutes.
- → What's the best type of bread to use?
Use good-quality white sandwich bread or pain de mie with a sturdy crumb. Brioche adds extra richness, while sourdough provides a tangy contrast. Avoid overly soft bread that will disintegrate when soaked.
- → How can I make this vegetarian?
Omit the ham and add sautéed mushrooms, caramelized onions, or fresh spinach between the bread layers. The béchamel and cheese provide plenty of richness and flavor without the meat.