Prepare the Meatloaf Mixture
Preheat the oven to 375°F (190°C).
In a large mixing bowl, combine ground chicken, breadcrumbs, egg, onion, garlic, salt, black pepper, parsley, and paprika. Mix until well incorporated.
Assemble the Meatloaf
Lay a sheet of parchment paper on a flat surface and spread the meat mixture into a rectangular shape (about ½ inch thick).
Layer the ham slices over the meat mixture, followed by the Swiss cheese slices.
Roll the Meatloaf
Using the parchment paper to help, gently roll the meat mixture into a loaf, sealing the edges tightly. Transfer the loaf onto a greased baking sheet or loaf pan, seam-side down.
Bake the Meatloaf
Bake for 40-45 minutes, or until the internal temperature reaches 165°F (74°C).
Make the Sauce
While the meatloaf bakes, melt butter in a saucepan over medium heat. Whisk in the flour and cook for 1-2 minutes until golden.
Gradually add milk, whisking constantly to avoid lumps. Stir in Dijon mustard, garlic powder, salt, and pepper. Simmer until thickened, about 3-5 minutes.
Serve
Let the meatloaf rest for 5-10 minutes before slicing. Drizzle with the creamy Dijon sauce and serve warm.