Preheat and prep: Heat the oven to 375°F (190°C). Grease a 9x13-inch baking dish with cooking spray or a bit of oil.
Make the sauce base: In a mixing bowl, whisk cream cheese, heavy cream, Dijon, and mayonnaise until smooth. If the cream cheese is stiff, microwave it for 10–15 seconds to soften before whisking.
Season the sauce: Stir in garlic powder, onion powder, lemon juice, pepper, salt, and paprika.
Taste and adjust salt or lemon as needed. The sauce should be tangy and well-seasoned.
Layer the chicken: Spread the cooked chicken evenly in the baking dish. Sprinkle a pinch of salt and pepper if your chicken is unseasoned.
Add the ham: Scatter the chopped ham over the chicken in an even layer.
Add the Swiss: Place Swiss slices or an even layer of shredded Swiss over the ham.
This helps lock in moisture and gives that classic cordon bleu flavor.
Pour the sauce: Spoon the sauce over the top and spread it gently into an even layer so every bite gets creamy coverage.
Make the topping: In a small bowl, mix Parmesan, almond flour, and melted butter until crumbly. Sprinkle evenly over the casserole.
Bake: Place the dish in the center of the oven and bake for 20–25 minutes until the edges are bubbling and the top is golden. If you want extra color, broil for 1–2 minutes at the end, watching closely.
Rest and serve: Let it rest for 5 minutes so the sauce sets.
Garnish with parsley. Serve with a green salad, roasted broccoli, or sautéed spinach.