01 - Heat a grill pan or skillet over medium-high heat until hot.
02 - Slice each chicken breast in half horizontally to create thinner cutlets. Drizzle with olive oil and season both sides with salt and pepper.
03 - Place chicken cutlets on the hot grill pan. Cook for 3–4 minutes per side until fully cooked through, reaching an internal temperature of 165°F. Remove from heat and let rest for 2 minutes.
04 - Lightly toast the ciabatta rolls cut-side down on the grill or in a toaster if desired.
05 - Spread a thin layer of pesto on the bottom half of each roll.
06 - Top each roll with a grilled chicken cutlet, a slice of mozzarella, tomato slices, and a handful of arugula or spinach.
07 - Spread mayonnaise on the top half of each roll if using.
08 - Place the top bun on each sandwich, slice in half diagonally, and serve immediately.