Preheat the oven to 375°F (190°C). Lightly grease a loaf pan or line a baking sheet with parchment paper.
In a large bowl, combine ground chicken, breadcrumbs, grated Parmesan, milk, egg, Dijon mustard, garlic powder, onion powder, Italian seasoning, salt, and black pepper. Mix gently until combined.
On a large piece of parchment paper, press the chicken mixture into a 10×12-inch rectangle.
Layer the deli ham evenly over the meat mixture, leaving a small border around the edges.
Place Swiss cheese slices evenly over the ham.
Using the parchment paper, carefully roll the meatloaf from one short end to the other, jelly-roll style. Press edges to seal and place seam-side down in the prepared pan or baking sheet.
Mix melted butter and breadcrumbs for the topping. Sprinkle the mixture evenly over the top of the meatloaf. Add shredded Swiss cheese if desired.
Bake for 50-60 minutes, or until the internal temperature reaches 165°F (74°C). If the top browns too quickly, cover loosely with foil during the last 15 minutes.
Let the meatloaf rest for 5-10 minutes before slicing.
To make the creamy Dijon sauce, melt butter in a saucepan over medium heat. Whisk in flour and cook for 1-2 minutes until golden.
Gradually whisk in chicken broth and heavy cream. Add Dijon mustard, garlic powder, onion powder, and black pepper.
Simmer the sauce for 3-5 minutes, stirring until thickened. Adjust salt and pepper to taste and keep warm.
Serve sliced meatloaf with the creamy Dijon sauce.