Preheat the oven to 200ºC, fan 180ºC, gas 6. Put the ciabatta pieces on a baking tray and bake for 8-10 minutes, until pale golden.
Meanwhile, make the salad dressing: put the anchovies in a small bowl and mash with a fork. Add the crushed garlic, grated parmesan, mayonnaise, vinegar and 4 tablespoons water, and mix well.
Put the lettuce leaves in a large bowl and scatter over half the chicken and half the baked ciabatta croutons. Pour in half the Caesar dressing and toss well, so each lettuce leaf is coated. Divide the salad between 4 plates, scatter over the remaining chicken and ciabatta croutons then drizzle with the remaining dressing. Top with the parmesan shavings and freshly ground black pepper to serve.