Place the egg in a pan of cold water and bring to the boil. Boil for one minute and then plunge into cold water to stop the cooking process.
Once the egg is cool enough to handle, crack the egg into a food processor and add the garlic, lime juice, Worcestershire sauce, anchovies and oil. Process well and add pepper to taste.
Heat a little olive oil in a frying pan, then fry the bread cubes until crisp and golden-brown, then drain on kitchen paper.
Place the cos lettuce into a large bowl.
To serve, pour the dressing over the leaves and add the fried bread cubes and parmesan. Toss well and serve at once.