Toast the cut sides of the ciabatta rolls in a dry skillet over medium heat for 3 minutes until crispy, leaving the outside soft.
Spread the basil pesto evenly over the toasted interior of both the top and bottom halves of the rolls.
Fold the prosciutto slices to create texture and place them on the bottom halves of the rolls, followed by an even layer of fresh mozzarella slices.
Layer the sliced tomatoes over the cheese, then sprinkle them with kosher salt and black pepper.
Toss the arugula with olive oil in a small bowl. Pile it onto the sandwiches, drizzle with balsamic glaze, add the top bun, and press down firmly before serving.
