Slice chicken breasts in half lengthwise to create 2 chicken cutlets from each chicken breast. Season both sides of chicken with Italian seasoning, salt, and pepper.
In a large skillet, heat 1 tablespoon of olive oil over medium-high heat. Cook chicken on both sides for about 5 minutes, or until the chicken reaches an internal temperature of 165 degrees.
Remove chicken from the pan.
Assemble the sandwiches by slicing the ciabatta rolls in half. Spread about 1 tablespoon of mayonnaise on one half of each roll. Spread about 1¼ tablespoons of pesto on the other half of each roll, then add a chicken cutlet to each sandwich.
Add 1 slice of mozzarella to each sandwich, followed by a tomato slice and romaine if desired.
Top the sandwich with the ciabatta roll with pesto. Lightly brush olive oil on top roll, then return sandwiches to the skillet. Cook each sandwich for 2 minutes per side, or until the mozzarella has fully melted.
Serve immediately and enjoy!