Preheat your oven or air fryer to 180°C.
Cook the buttermilk tenderloins according to the pack instructions, or until golden and cooked through.
Cut the ciabatta loaf or baguette in half lengthwise. Spread the mayonnaise over the base of the ciabatta, then arrange the chicken on top. Spoon the tomato sauce over the chicken, then arrange the sliced mozzarella on top. Sprinkle over the parmesan. Return the sandwich to the oven or air fryer for 5-10 minutes, or until the cheese has melted.
Remove the sandwich from the oven and top it with the sliced tomatoes, pesto and basil. Place the top half of the ciabatta on top and press down lightly to sandwich the two layers together. Cut into portions to serve.