01 - Slice chicken breasts horizontally to form thin cutlets. Drizzle with olive oil and season both sides with salt and black pepper.
02 - Preheat grill pan or skillet over medium-high heat. Grill the chicken cutlets for 4–5 minutes per side, or until the meat is fully cooked and golden. Remove from heat and let rest for 2 minutes, then slice if preferred.
03 - If desired, lightly butter the inside of each roll. Toast cut sides against the grill or skillet until golden brown.
04 - Generously spread pesto onto the bottom half of each roll. Layer grilled chicken slices, fresh mozzarella, tomato slices, and arugula or spinach leaves, then cap with the remaining halves.
05 - Serve warm or at room temperature.