Heat olive oil in a large heavy pan over medium heat. Season the chicken cutlets on both sides with salt and pepper. Add the cutlets to the preheated pan and cook until golden brown on the bottom, 3-4 minutes. Flip the cutlets and cook until browned on the other side and a thermometer inserted in the center reads 165° F, 2-3 minutes longer. Remove the chicken from the pan and keep warm.

Spread 1 tablespoon of pesto on 1 side of each bread slice. Layer 4 of the bread slices with 2 slices of tomato, 1 chicken cutlet, 2 slices of mozzarella, and 3-4 fresh basil leaves (if desired) each, then top with the remaining 4 slices of bread, pesto-side down.

Heat a panini press or a large heavy pan (or grill pan) over medium heat and brush with olive oil. If you’re cooking in a pan instead of a panini press, use a second heavy skillet weighed down with a few cans to simulate the top of the panini press, and flip the panini halfway through the cooking time.

Add two of the sandwiches to the panini press and cook for 5 minutes, or until warmed through and crispy on both sides.

Repeat with the remaining sandwiches. Serve hot.