6 cups cooked chicken, diced
1 1/2 cups cooked ham, diced
8 slices Swiss cheese
4 1/2 tablespoons butter
4 1/2 tablespoons flour
3 1/4 cups milk
2 tablespoons lemon juice
2 teaspoons Dijon mustard
1/2 teaspoon paprika
1 1/2 cups Panko bread crumbs
6 1/2 tablespoons butter, melted
1/2 teaspoon salt
2 teaspoons dried parsley

Preheat oven to 350 degrees Fahrenheit. Lightly spray a 9 x 13-inch baking dish with cooking spray. Sprinkle chicken and ham evenly in the dish. Cover with Swiss cheese slices.

Melt the 4 1/2 tablespoons butter in a large pot. Add the flour to form a roux. Slowly whisk in the milk until smooth. Continue to whisk until the sauce starts to thicken, which takes about 2 to 3 minutes. Remove from the heat, and stir in the lemon juice, mustard, paprika, salt and pepper. Pour sauce over the casserole.

For the topping, combine the Panko bread crumbs, 6 1/2 tablespoons melted butter, seasoning salt and parsley. Sprinkle over the casserole.

Bake uncovered for 45 to 55 minutes, or until golden brown on top. Let sit for 5 minutes before serving.