01 - Warm a grill pan or skillet over medium-high heat.
02 - Slice chicken breasts horizontally to form even, thinner cutlets. Drizzle with olive oil and season both sides with salt and ground black pepper.
03 - Grill chicken cutlets for 4 to 5 minutes per side until fully cooked and golden. Remove from heat, rest for 2 minutes, then slice if desired.
04 - If desired, lightly butter the inside of each ciabatta roll. Toast cut sides on the grill pan or skillet until golden.
05 - Evenly spread a generous layer of basil pesto onto the bottom half of each toasted roll.
06 - Layer grilled chicken, mozzarella slices, tomato, and baby arugula or spinach over the pesto. Top with the remaining half of each roll.
07 - Serve immediately while warm, or at room temperature if preferred.