To make the croutons: Heat olive oil in a pan with garlic cloves. Cook the cubed bread in batches until golden and crisp. Remove garlic when it begins to brown. Drain on kitchen towel. Croutons will keep for at least a week in an airtight container.
To make the dressing: Place egg, mustard, garlic, lemon juice and peel, an¬chovies, Worcestershire sauce and Parmesan in a food processor and whizz to combine. With the motor running, gradually pour in oil and process until smooth and creamy.
To make the salad: Roughly chop the lettuce leaves, chopping the larger ones and keeping the smaller inner leaves whole. Just before serving, toss leaves with two thirds of the dressing, bacon and croutons. Spoon over remaining dressing and scatter with parmesan shavings.
* Note: Although some recipes use a raw egg, a coddled egg will give the dressing a smoother, creamier texture. (Pregnant women should go for this option.) To coddle an egg, bring a small pot of water to fast boil and gently place the egg into it and cook for 45 seconds.