Mix flour, milk, eggs and a little salt. Dip toast slices in it. Cut cheese into medium-thin slices and place between two slices of toast. Season with pepper or a fresh basil leaf if desired. Toast everything together in the olive oil at a low temperature so that the heat melts the cheese topping. This will go a tiny bit faster if you cover the frying pan. Once one side is browned golden, turn to the other side.