Follow these straightforward steps to create your Chicken Cordon Bleu Casserole effortlessly:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Prepare Baking Dish: Grease a 9×13-inch baking dish with cooking spray or butter.
3. Mix Chicken and Ham: In a large bowl, combine the shredded chicken and chopped ham. Mix well.
4. Add Cheeses: Fold in half of the shredded Swiss cheese and half of the cheddar cheese to the chicken-ham mixture.
5. Prepare Sauce: In another bowl, whisk together the sour cream, milk, Dijon mustard, garlic powder, onion powder, salt, and pepper until well blended.
6. Combine Ingredients: Pour the sauce over the chicken and ham mixture, stirring to combine.
7. Transfer Mixture: Spread the mixture evenly into the greased baking dish.
8. Top with Breadcrumbs: Sprinkle the remaining Swiss and cheddar cheeses over the top. Then, add an even layer of breadcrumbs for extra crunch.
9. Bake: Place the casserole in the preheated oven and bake for 35-40 minutes, or until bubbly and golden brown.
10. Garnish and Serve: Once cooked, remove from the oven and let it cool for a few minutes. Garnish with fresh chopped parsley before serving.

These steps will guide you in crafting a fantastic Chicken Cordon Bleu Casserole that will leave everyone wanting more!