Boil, steam or microwave potatoes until tender. Drain. Cool to room temperature.
Meanwhile, to make croutons, toss bread with butter in a bowl. Season with salt and pepper. Spread out on an oven tray. 3. Cook in a hot oven (200C) for about 15 minutes, or until golden brown. Cool on tray for 10 minutes.
Cook bacon in a heated, non-stick frying pan, stirring occasionally, for about 5 minutes, or until browned and crisp. Drain on absorbent paper towel.
To make caesar salad dressing, combine all ingredients in a medium jug. Whisk until thoroughly combined.
Just before serving, toss potatoes with bacon, onion and dressing in a large bowl. Season with salt and pepper.
To serve, arrange lettuce leaves on a serving plate and top with potato mixture. Sprinkle with croutons and parsley leaves.