Chicken Cordon Bleu Casserole with Dijon Cream Sauce

• Layering broad chicken pieces instead of shredding them finely preserves the cordon bleu idea. Each serving gets recognizable chicken, ham, cheese, and sauce.
• Dijon and a small amount of lemon balance the rich dairy and cured meat. They sharpen the sauce without making it taste strongly acidic.
• Panko is toasted in butter before baking. Starting it golden creates a reliably crisp surface during the short oven time needed to heat cooked chicken. It also makes doneness easier to judge.

Ingredient notes

• Cooked chicken: Slice or tear the meat into broad, flat pieces. A mixed rotisserie chicken works well, but remove the seasoned skin so it does not soften beneath the sauce. Keep pieces about 1 inch wide.
• Ham: Choose thinly sliced deli ham rather than thick cubes. Folded ribbons create even salty accents and allow the casserole to cut without pieces tumbling out.
• Swiss cheese: Grate most of the cheese for smooth melting, then reserve a few thin strips for visible pockets. Gruyère works when a stronger nutty flavor is welcome.
• Dijon sauce: Stock keeps the cream from feeling heavy. Dijon, lemon juice, and black pepper provide contrast, while flour gives enough body for tidy portions.
• Panko: These coarse crumbs retain more texture than fine breadcrumbs. Toast them in butter before assembly because the filling needs only a brief bake. Cool briefly on a plate so they stay loose during assembly.

1. 1Toast the crumb topping

   Heat the oven to 375°F (190°C). Melt 28 g butter in a skillet over medium heat. Add the panko and cook for 3 to 4 minutes, tossing often, until most crumbs are pale gold. Stir in parsley and move the mixture to a plate. Stop before deep brown because the topping will color further in the oven.

2. 2Thicken the Dijon sauce

   Melt the remaining butter in a saucepan. Stir in flour and garlic powder for 1 minute. Gradually whisk in stock and milk, then simmer for 3 to 4 minutes until the sauce leaves a clear trail behind the whisk. Remove from heat and add Dijon, lemon juice, pepper, and 85 g Swiss cheese. Stir until smooth.

   

3. 3Create distinct layers

   Arrange half the chicken in a lightly buttered 9-inch square dish. Cover with half the folded ham ribbons and one-third of the remaining Swiss. Spoon over one-third of the sauce. Repeat the chicken, ham, cheese, and sauce. Finish with the last sauce and cheese, spreading gently without mixing the layers. Scatter the toasted panko loosely over the surface.

   

4. 4Bake and settle

   Bake uncovered for 22 to 25 minutes, until the sauce bubbles at several edges and the cheese forms golden spots beneath the crumbs. Rest for 10 minutes before cutting into 6 rectangles. Use a thin spatula to reach the bottom layer. If the center looks loose at first, wait rather than extending the bake and drying the cooked chicken. Keep the top uncovered while it settles.

• Taste the ham before seasoning the sauce. Cured meat and Swiss vary in salt, so added salt may be unnecessary.
• Fold ham into loose ribbons. Flat, compact sheets create a slippery layer that separates when the casserole is served.
• Watch for a whisk trail in the sauce. If it closes immediately, simmer another minute before adding cheese.
• Toast panko only to pale gold. Dark crumbs can become bitter during the final uncovered bake.
• Rest the dish before cutting. The dairy sauce thickens as it cools and grips the layered chicken without spilling beneath each carefully lifted serving on the plate.

Pair each rich rectangle with lemon-dressed green beans, roasted asparagus, or a bitter-leaf salad. Six servings are substantial without pasta or rice underneath. If feeding 8, offer small portions with crusty bread and a large salad. Keep extra Dijon at the table for sharper bites, but taste first because the sauce already carries a clear mustard note. Add parsley for color.