1. Prepare the Chicken: Lay each boneless, skinless chicken thigh flat. If they are very thick, gently pound them to an even 1/2-inch thickness using a meat mallet or the bottom of a heavy pan. Season both sides lightly with salt and pepper.

2. Assemble the Filling: On each flattened chicken thigh, place one slice of ham, followed by one slice of Swiss cheese. Ensure the ham and cheese cover most of the chicken surface, leaving a small border around the edges.

3. Roll Them Up: Carefully roll each chicken thigh tightly, starting from one end. Tuck in the sides as you roll to keep the filling secure. If needed, you can secure the rolls with a toothpick.

4. Set Up the Breading Station: Prepare three shallow dishes. In the first, place the all-purpose flour. In the second, whisk the egg until it’s well beaten. In the third, combine the breadcrumbs, grated Parmesan cheese, garlic powder, and onion powder, mixing well.

5. Bread the Chicken: Dredge each rolled chicken thigh first in the flour, shaking off any excess. Then dip it into the beaten egg, ensuring it’s fully coated. Finally, roll it in the breadcrumb mixture, pressing gently to make sure the crumbs adhere completely to all sides.

6. Sear for Golden Perfection: Heat the olive oil in a large oven-safe skillet over medium-high heat. Once hot, carefully place the breaded chicken rolls seam-side down in the skillet. Sear for 3-4 minutes per side, until they are golden brown and crispy all over.

7. Finish in the Oven: Transfer the skillet to a preheated oven at 375 F (190 C). Bake for 15-20 minutes, or until the chicken is cooked through and reaches an internal temperature of 165 F (74 C) and the cheese is melted and bubbly. If you used toothpicks, remove them before serving.

8. Rest and Serve: Let the chicken rest for 5 minutes before slicing and serving. This allows the juices to redistribute, keeping the chicken moist and tender.