1. Wash and dry the chicken. Remove the tenderloin and set aside for another use. Season both sides lightly with kosher salt and pepper. Using a fork, spread the roasted garlic, if using, all over the chicken breasts. On the top side of the breast, lay 1 slice of pancetta over the lower portion of the breast, wrapping it snugly so it adheres. Lay a sage leaf on the center of the breast, and wrap the upper portion with a second slice of pancetta. Turn the breast over and wrap a third slice of pancetta over the back of the breast. Repeat with the remaining chicken, transferring the pieces to a plate as you go. (The chicken can be made in advance up to this point. Just wrap tightly in plastic wrap & refrigerate.).
2. Preheat the oven to 450 degrees Fahrenheit.
3. Toss the potatoes, lemon, 10 sage leaves, oil, and a pinch of kosher salt and pepper in a large bowl until well coated.
4. Meanwhile, heat a large cast-iron skillet or grill pan over high heat until it is very hot. Drizzle the pancetta-wrapped chicken with oil and place in the pan with the sage leaf side down. Cook over high heat until the pancetta is brown, about 5 minutes. Turn the breasts over and transfer the pan to the upper rack of the oven for 15 minutes, or until cooked through.
5. Remove the chicken from the pan, transfer to a plate and set aside. Deglaze the pan with the wine over high heat. Reduce the wine until almost evaporated, and add the chicken stock. Continue to cook until reduced by half.