Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease it.

Place one chicken breast at a time between two pieces of plastic wrap. Use a meat mallet or rolling pin to pound the chicken to an even thickness of about 1/4 inch. This is key to ensuring it cooks evenly and rolls easily. Season both sides of the flattened chicken breasts generously with salt and pepper.

On each flattened chicken breast, lay one slice of ham and then one slice of Swiss cheese, leaving a 1/2-inch border around the edges to help seal.

Starting from one of the shorter ends, roll each chicken breast up tightly, tucking in the sides as you go to enclose the filling completely. Secure each roll with 2-3 toothpicks to prevent it from unravelling during baking.

Set up a breading station with three shallow dishes. In the first, combine the flour, paprika, and garlic powder. In the second, whisk the eggs with the water or milk. In the third, place the Panko breadcrumbs.

Working with one chicken roll at a time, first dredge it in the seasoned flour mixture, shaking off any excess. Next, dip it completely in the egg wash, allowing the excess to drip off. Finally, press the roll firmly into the Panko breadcrumbs, ensuring it's fully and evenly coated all over.

Arrange the breaded chicken rolls seam-side down on the prepared baking sheet. Drizzle the melted butter evenly over the tops of each roll. This helps the Panko get extra crispy and golden brown.

Bake for 25-30 minutes, or until the chicken is cooked through and the coating is golden brown and crisp. The internal temperature should register 165°F (74°C) on an instant-read thermometer when inserted into the thickest part of the chicken (not the cheese filling).

Remove the chicken from the oven and let it rest on the baking sheet for 5-10 minutes before serving. This crucial step allows the juices to redistribute, ensuring the chicken is moist and tender. Carefully remove all toothpicks before slicing and serving warm.