Save to Pinterest My neighbor knocked on my door one Saturday morning with a casserole dish still warm from her oven. She'd made too much, she said, and thought I might like to try her Croque Monsieur Casserole. One bite and I was hooked—crispy golden edges, creamy center, that unmistakable nuttiness of Gruyère melting into béchamel. I asked for the recipe immediately and have been making it for brunch gatherings ever since.
The first time I served this at a family brunch, my sister-in-law stood at the counter and ate three helpings straight from the pan. She didn't even bother with a plate. My brother joked that she'd never been that enthusiastic about anything he'd cooked, and we all laughed while scraping up the last cheesy bits from the corners.
Ingredients
- White sandwich bread: Removing the crusts helps the bread absorb the custard evenly, and soft white bread becomes beautifully custardy without turning tough.
- Unsalted butter: Buttering each slice before layering adds richness and helps the top turn golden and crisp in the oven.
- Gruyère cheese: This nutty, slightly sweet cheese is traditional and melts like a dream, but Swiss works well if Gruyère is hard to find.
- Whole milk and heavy cream: The combination creates a luscious custard base that binds everything together without feeling too heavy.
- Large eggs: They give structure to the custard and help the casserole puff up as it bakes.
- Cooked ham: Use good quality deli ham or leftover holiday ham, sliced thin so it layers neatly between the bread.
- All-purpose flour: It thickens the béchamel into a silky sauce that blankets the top layer beautifully.
- Ground nutmeg: Just a pinch adds warmth and a subtle complexity that makes people wonder what the secret ingredient is.
Instructions
- Preheat and Prep Your Dish:
- Set your oven to 375°F and generously butter a 9x13-inch baking dish so nothing sticks. This step also adds a little extra richness to the edges.
- Make the Béchamel Sauce:
- Melt butter in a saucepan, whisk in flour, and cook for a minute until it smells nutty but not browned. Slowly add milk while whisking constantly to avoid lumps, then let it thicken into a smooth, velvety sauce before seasoning with nutmeg, salt, and pepper.
- Butter the Bread:
- Spread softened butter on one side of each slice and arrange half of them buttered side down in your dish. This creates a crispy bottom layer that contrasts beautifully with the creamy interior.
- Layer Ham and Cheese:
- Lay half the ham over the bread, then sprinkle half the Gruyère on top. Repeat with the remaining bread, ham, and cheese, building those classic Croque Monsieur flavors into every bite.
- Pour the Custard:
- Whisk eggs, milk, cream, and a pinch of salt together and pour the mixture evenly over the casserole. Press down gently so the bread soaks up the custard and nothing floats.
- Top with Béchamel:
- Pour your béchamel sauce over everything and spread it to the edges. This creates a golden, bubbling top that's irresistible.
- Bake Until Golden:
- Slide the dish into the oven and bake for 35 to 40 minutes until it's puffed, golden, and bubbling at the edges. Let it rest for 10 minutes so it sets and doesn't fall apart when you serve it.
Save to Pinterest I brought this to a potluck once and watched a friend who claimed she didn't like ham take a tentative spoonful, then come back for seconds. She said it reminded her of a café she'd visited in Paris years ago, and that memory alone made her fall in love with it. Food has a funny way of taking us places we haven't been in a long time.
Making It Ahead
You can assemble the entire casserole the night before, cover it tightly with plastic wrap, and refrigerate it overnight. In the morning, let it sit at room temperature for 20 minutes while the oven preheats, then bake as directed. The flavors actually deepen after a night in the fridge, and the bread soaks up even more of that custardy goodness.
Vegetarian and Flavor Variations
Skip the ham entirely and layer in sautéed mushrooms, spinach, or caramelized onions for a vegetarian version that's just as satisfying. I've also tucked a thin layer of Dijon mustard between the bread slices for a sharper, more traditional Croque Monsieur bite. If you want to go all out, add a handful of fresh thyme leaves to the béchamel for an herby twist that feels almost fancy.
Serving Suggestions
This casserole is rich, so I always serve it with something bright and crisp to balance it out. A simple arugula salad with lemon vinaigrette or a pile of lightly dressed mixed greens works perfectly. A chilled glass of Chardonnay or a sparkling water with lemon feels right alongside it, and if you're serving brunch, fresh fruit or berries on the side add a pop of color and sweetness.
- Pair it with a tangy green salad to cut through the richness.
- Serve with roasted asparagus or green beans for a more elegant presentation.
- Offer crusty bread on the side for anyone who wants to soak up extra béchamel.
Save to Pinterest This casserole has become my go-to whenever I want to impress without spending hours in the kitchen. It's the kind of dish that makes people feel cared for, and honestly, that's the best part of cooking.
Recipe FAQs
- → Can I prepare this casserole ahead of time?
Yes, assemble the casserole up to 24 hours in advance. Cover tightly and refrigerate, then bake as directed, adding 5-10 minutes to the cooking time if baking from cold.
- → What cheese can I substitute for Gruyère?
Swiss cheese is the closest substitute, or try Emmental, Comté, or even a sharp white cheddar for a different flavor profile while maintaining good melting properties.
- → How do I make this vegetarian?
Omit the ham and add sautéed mushrooms, wilted spinach, or caramelized onions between the bread layers for a flavorful meatless version.
- → Why remove the bread crusts?
Removing crusts allows the custard and béchamel to soak evenly into the bread, creating a softer, more uniform texture throughout the casserole.
- → Can I use day-old bread?
Absolutely! Slightly stale bread actually works better as it absorbs the custard mixture without becoming too soggy, resulting in a better texture after baking.
- → What should I serve with this casserole?
A simple green salad with Dijon vinaigrette balances the richness perfectly. Fresh fruit, roasted asparagus, or a light soup also pair beautifully for brunch or dinner.