Pin It My neighbor Claire brought this to a Sunday gathering, and I watched six adults fight politely over the last square. The smell of melted Gruyère and toasted bread filled her kitchen, and when she cut into it, steam rose in soft clouds. I asked for the recipe immediately. She laughed and said it was just a croque monsieur that got lazy and turned into a casserole, but I knew better—this was comfort in a dish.
The first time I made this for my family, my brother-in-law asked if I'd gone to culinary school. I hadn't, but I had learned that good butter, real Gruyère, and patience with béchamel could fool anyone. My sister kept scraping her fork across her plate to catch every bit of sauce. That's when I knew this recipe had earned a permanent spot in my rotation.
Ingredients
- White sandwich bread: Remove the crusts so the bread soaks up the custard evenly, and use sturdy slices that won't fall apart when layered.
- Unsalted butter: Softened butter spreads easily on bread and adds richness without making the dish too salty, especially since ham and cheese bring their own salt.
- Gruyère cheese: This is the soul of the dish—nutty, melty, and slightly sweet. Swiss works in a pinch, but Gruyère is worth the extra dollar.
- Whole milk and heavy cream: The custard base needs both for body and silkiness. Don't skip the cream or it won't set properly.
- Large eggs: They bind everything together and give the casserole structure so it slices cleanly instead of falling apart.
- Cooked ham: Use deli ham or leftover holiday ham. I prefer a little thickness so each bite has presence.
- All-purpose flour: This thickens the béchamel. Measure it level or the sauce will turn gluey.
- Ground nutmeg: Just a whisper of nutmeg makes béchamel taste like it came from a French kitchen instead of a Tuesday night.
Instructions
- Preheat and Prep the Dish:
- Set your oven to 375°F and butter a 9x13-inch baking dish generously so nothing sticks. This step matters more than you think.
- Make the Béchamel:
- Melt 2 tablespoons butter in a saucepan over medium heat, whisk in the flour, and cook for one minute until it smells toasty. Slowly pour in 1 1/4 cups 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 and arrange half of them buttered side down in the dish. This creates a golden, crispy bottom layer.
- Layer Ham and Cheese:
- Place half the ham slices over the bread, then sprinkle half the Gruyère on top. Repeat with remaining bread, ham, and cheese.
- Pour the Custard:
- Whisk together eggs, 1 cup milk, cream, and a pinch of salt, then pour it evenly over the casserole. Press down gently with a spatula so the bread absorbs the liquid.
- Top with Béchamel:
- Pour the warm béchamel sauce over everything and spread it to the edges. It will look like too much, but it's not.
- Bake Until Golden:
- Bake uncovered for 35 to 40 minutes until the top is puffed, golden, and bubbling at the edges. Let it rest for 10 minutes before slicing so the layers set.
Pin It I made this on a rainy Saturday when my best friend was going through a breakup. We ate it straight from the pan with forks, no plates, no pretense. She said it tasted like a hug, and I realized that's exactly what this dish is—something warm and indulgent that makes hard days feel softer.
How to Know When It's Done
The casserole is ready when the top turns golden brown and the edges bubble with melted cheese. If you insert a knife into the center, it should come out mostly clean with just a little creamy custard clinging to it. The bread will puff up slightly as the eggs set, and the whole dish will smell like a French café on a Sunday morning.
Make Ahead and Storage
You can assemble the entire casserole the night before, cover it tightly with plastic wrap, and refrigerate it until morning. Let it sit at room temperature for 20 minutes before baking, then add 5 to 10 minutes to the bake time since it's starting cold. Leftovers keep in the fridge for up to three days and reheat beautifully in a 350°F oven covered with foil.
Serving Suggestions and Variations
I love serving this with a simple arugula salad dressed in lemon and olive oil to cut through the richness. A glass of chilled Chardonnay or sparkling water with lemon feels right alongside it. For a vegetarian version, skip the ham and add sautéed mushrooms or wilted spinach between the layers.
- Brush Dijon mustard between the bread layers for a sharper, more traditional croque monsieur flavor.
- Swap Gruyère for aged white cheddar if you want something a little less expensive but still flavorful.
- Add a handful of fresh thyme leaves to the custard for an herby, earthy note.
Pin It This casserole has become my go-to when I want to impress without stress. It's proof that the best recipes are the ones that taste fancy but feel like home.
Recipe FAQs
- → Can I make this casserole ahead of time?
Yes, assemble the casserole up to 24 hours in advance, cover tightly with plastic wrap, and refrigerate. Pour the béchamel sauce over just before baking and add 5-10 minutes to the baking time if baking straight from the fridge.
- → What type of bread works best for this dish?
White sandwich bread is traditional and soaks up the custard beautifully. Brioche or challah add extra richness, while sourdough provides a tangy contrast. Remove crusts for the most authentic texture.
- → Can I substitute the Gruyère cheese?
Absolutely. Swiss cheese is the closest substitute, offering similar melting properties. Comté, Emmental, or a sharp white cheddar also work well, though they'll slightly alter the flavor profile.
- → How do I make this vegetarian?
Omit the ham and layer in sautéed mushrooms, caramelized onions, or fresh spinach instead. You can also add roasted vegetables like zucchini or bell peppers for added depth and nutrition.
- → What should I serve alongside this casserole?
A crisp green salad with Dijon vinaigrette balances the richness perfectly. Roasted asparagus, sautéed green beans, or a simple arugula salad also pair beautifully. For brunch, serve with fresh fruit.
- → How do I know when the casserole is done?
The top should be golden brown and puffed, with edges bubbling. A knife inserted in the center should come out mostly clean. Let it rest for 10 minutes after baking so the custard sets properly for cleaner slicing.