Roughly chop all the eggs and place in a large glass bowl.
Add the mayo, Caesar dressing, mustard, vinegar, Parmesan, salt and pepper and stir gently to combine. Taste and add additional salt and pepper if desired.
Toast bread, top each of 4 slices with a lettuce leaf then a generous helping of the egg salad, and then the remainig 4 slices of toasted bread. I like to put some Caesar dressing on my toasted bread slices as well, so it doesn't seem to dry - that is optional depending on your preference.
Slice your sandwiches, if that's how you roll, and enjoy!