01 - Preheat a grill pan or skillet over medium-high heat.
02 - Slice each chicken breast in half horizontally for thinner cutlets. Drizzle with olive oil and season with salt and pepper.
03 - Grill chicken cutlets for 3–4 minutes per side, or until fully cooked (internal temperature 165°F/74°C). Remove and let rest for 2 minutes.
04 - Toast ciabatta rolls lightly, if desired.
05 - Spread a thin layer of pesto on the bottom half of each roll.
06 - Top each with a grilled chicken cutlet, a slice of mozzarella, tomato slices, and a handful of arugula or spinach.
07 - Optionally, spread mayonnaise on the top half of the rolls.
08 - Close sandwiches, slice in half, and serve immediately.