Chicken Cordon Bleu Casserole

I pulled this casserole together on a Tuesday night when I had leftover chicken and a craving for something rich but not fussy. The idea of turning Chicken Cordon Bleu into a one-dish bake felt genius at the time, and the moment that cheese sauce bubbled up around the edges, I knew I'd stumbled onto something worth keeping. It smelled like a French bistro had taken over my kitchen, and I didn't mind one bit.

The first time I made this for friends, someone asked if I'd been to culinary school. I laughed and told them it was leftovers and a little creativity, but secretly I was thrilled. Watching everyone go back for seconds made me realize this wasn't just dinner, it was the kind of dish that turns a regular evening into something people remember.

Ingredients

• Cooked chicken breast: Rotisserie chicken is your best friend here, but any leftover roasted or poached chicken works beautifully.
• Cooked ham: I like a good deli ham with a little smoke to it, diced small so it weaves through every bite.
• Swiss cheese: It melts like a dream and brings that nutty, slightly sweet flavor that makes Cordon Bleu so recognizable.
• Milk: Whole milk gives the sauce body, but 2% will do just fine if that's what you have on hand.
• Cream cheese: This is what makes the sauce silky and rich without needing a roux that takes forever.
• Unsalted butter: Used twice, once in the sauce and once to toast the breadcrumbs, so don't skip it.
• All-purpose flour: Just enough to thicken the sauce without making it gummy.
• Dijon mustard: A small spoonful adds that tangy kick you expect from the classic dish.
• Garlic powder: Keeps the flavor mellow and blends right into the sauce without any sharp bits.
• Black pepper and salt: Season thoughtfully, the ham and cheese already bring plenty of salt.
• Panko breadcrumbs: They stay crispier than regular breadcrumbs and give you that perfect golden top.
• Parmesan cheese: Grated fresh if you can, it adds a salty, nutty finish to the topping.
• Fresh parsley: Optional, but a little green on top makes the whole dish look like you tried harder than you did.

Instructions

Prep the dish:

Preheat your oven to 375°F and grease a 9x13-inch baking dish lightly with butter or cooking spray. This keeps everything from sticking and makes cleanup so much easier.

Build the base:

Spread your chicken evenly across the bottom, then scatter the ham over it and sprinkle on 1 1/2 cups of Swiss cheese. The layers don't have to be perfect, just make sure everything gets a little of each.

Make the sauce:

Melt 2 tablespoons of butter in a medium saucepan over medium heat, whisk in the flour, and let it cook for about a minute until it smells toasty. Slowly pour in the milk, whisking constantly so no lumps form.

Finish the sauce:

Stir in the cream cheese, Dijon, garlic powder, salt, and pepper, and keep stirring until the cream cheese melts and the sauce thickens enough to coat the back of a spoon. It should take 3 to 4 minutes and smell incredible.

Assemble the casserole:

Pour the sauce over the chicken and ham, letting it seep into all the corners, then sprinkle the remaining 1/2 cup of Swiss cheese on top. It's okay if it looks messy, it all evens out in the oven.

Add the topping:

Toss the Panko with melted butter, Parmesan, and parsley in a small bowl, then scatter it evenly over the casserole. This is what gives you that irresistible golden crunch.

Bake and rest:

Slide the dish into the oven and bake for 30 to 35 minutes, until the top is golden and the edges are bubbling. Let it sit for 5 minutes before serving so the sauce settles and you don't burn your mouth.

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There's something about the way this casserole fills the house with the smell of butter and cheese that makes everyone drift into the kitchen before it's even done. My partner once said it reminded him of Sunday dinners at his grandmother's place, and I took that as the highest compliment. It's the kind of food that wraps you up and makes you feel cared for.

Swaps and Substitutions

If you can find Gruyère, swap it for the Swiss and prepare for an even richer, nuttier flavor that feels downright fancy. Turkey works just as well as chicken, and I've used leftover Thanksgiving turkey more than once with amazing results. For a lighter version, you can use half-and-half instead of whole milk and reduce the butter in the topping, though you'll sacrifice a little of that indulgent texture.

Serving Suggestions

I love pairing this with a simple arugula salad dressed in lemon vinaigrette to cut through all that creamy richness. Steamed green beans or roasted asparagus work beautifully too, and if you're feeding a crowd, garlic bread on the side never hurts. A crisp white wine like Chardonnay or a light Pinot Grigio makes the whole meal feel a little more special without any extra effort.

Storage and Reheating

Leftovers keep covered in the fridge for up to three days, and they reheat surprisingly well in the oven at 350°F for about 15 minutes. The microwave works in a pinch, but the topping won't stay as crispy. I've even frozen individual portions in airtight containers for up to two months, then thawed them overnight in the fridge before reheating.

• Cover the casserole with foil when reheating to keep it from drying out.
• If the topping loses its crunch, pop it under the broiler for a minute or two.
• Let frozen portions come to room temp for 10 minutes before reheating for more even warming.

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This casserole has earned a permanent spot in my weeknight rotation, and I hope it does the same for you. There's comfort in knowing you can pull together something this satisfying without breaking a sweat.

Recipe Questions & Answers

→ Can I substitute the Swiss cheese?

Gruyère cheese offers a richer, nuttier flavor that complements this dish well as a substitute for Swiss.

→ Is pre-cooked chicken necessary?

Using rotisserie or pre-cooked chicken helps speed preparation and ensures even cooking in the casserole.

→ How do I achieve a crispy topping?

Combine panko breadcrumbs with melted butter and Parmesan cheese, then sprinkle evenly over the casserole before baking.

→ Can this dish be prepared ahead?

Assemble the layers and refrigerate uncooked for up to 24 hours before baking for convenience.

→ What sides pair well with this dish?

Crisp green salads or steamed vegetables balance the richness and add freshness to the meal.