I was shocked when I saw Alton Brown making a grilled cheese sandwich of some sort using olive oil instead of butter. But, why not? Olive oil is supposed to be good for you… When I make a grilled cheese I use the very smallest slice of butter, like half a pat, cook it on one side, and flip and let the other side do as it will - as long as the cheese is melted and the bread somewhat scorched. It’s presented butter-cooked side up and the happy recipient is none the wiser.