Prepare the Chicken: Begin by pounding the chicken breasts to an even thickness, ensuring uniform cooking. Season them with Italian seasoning, salt, and pepper for added flavor.
Cook the Chicken: Heat your skillet or grill and cook the chicken until it reaches an internal temperature of 165°F. Let it rest before slicing to retain its juices.
Assemble the Sandwich: Spread pesto on the sourdough slices, add the chicken, cheese, and tomato slices, and brush the outer bread surfaces with olive oil.
Toast the Sandwich: In a skillet or on a grill, toast the sandwich until the bread is golden and the cheese has melted, flipping once to ensure even browning.
Serve: Once cooked to perfection, serve the sandwich warm, allowing the flavors to meld together beautifully.