Ready to turn these ingredients into a comforting masterpiece? Let’s get started!

1. Preheat your oven to 350°F (175°C).
2. In a medium saucepan, melt the butter over medium heat. Stir in the flour and cook for about 1-2 minutes until it forms a paste.
3. Gradually whisk in the milk and heavy cream, ensuring there are no lumps. Bring the mixture to a simmer, stirring continuously until it thickens.
4. Add the Dijon mustard, salt, and pepper to the sauce. Taste and adjust seasoning if needed.
5. In a large mixing bowl, combine the shredded chicken, diced ham, and Swiss cheese. Pour the sauce over and mix well to coat everything evenly.
6. Transfer the mixture into a greased 9×13-inch baking dish, spreading it out evenly.
7. In a small bowl, mix together the breadcrumbs and Parmesan cheese. Sprinkle this mixture over the casserole.
8. Bake in the preheated oven for 25-30 minutes, until the top is golden brown and the casserole is bubbling around the edges.
9. Let it cool for a few minutes before serving. Enjoy the warm, creamy, and crunchy delight!