1.Turn on the oven to 180°C/350°F and let it heat up.
2.Put the oil into a large bowl; add the bread and turn it over to cover both sides in oil. Place the bread slices on an oven tray. Put the tray in the oven and toast the slices for about 8 minutes, then turn them over and toast the other side for about 8 minutes or until crisp. These are called croûtons.
3.Meanwhile, place a large frying pan on the stove and turn on the heat to medium-high. Put the prosciutto into the pan and cook until it is crisp. Use tongs to lift the prosciutto onto a plate covered with absorbent paper to soak up the fat. When the prosciutto is cool enough to touch, chop it coarsely.
4.Half-fill a large frying pan with water. Turn the stove on to high and boil the water. Break one egg into a small bowl or cup, then slide the egg into the pan of boiling water, being careful not to break the yolk. Do this, one at a time, with the rest of the eggs. When all the eggs are in the pan, allow the water to boil again. Put a lid on the pan. Turn off the heat; leave for about 4 minutes or until the yolks are covered with a light film of set egg white.
5.Place a piece of absorbent paper on a plate. Use a slotted spoon to lift one egg out of the water, resting the spoon on the plate to soak up the poaching liquid. Do this, one at a time, with the rest of the eggs.
6.Put the lettuce, cheese, croûtons, prosciutto and dressing into a large bowl; mix them together with tongs. Divide the salad between four serving dishes; put a poached egg on top of each.
You can use bacon instead of prosciutto, if you like.Note