Some people already know this; this is for the people who do not. I had been eating leftover pizza for decades before it occurred to me.
Specifically, I was home by myself and procrastinating about putting a cold slice in the toaster oven to make it become a warm and floppy slice, when the solution revealed itself: Use a skillet.
A quick Google consultation showed that the insight was by no means original. Our sibling Lifehacker site had mentioned it a few years earlier, albeit with some complicated business about tenting the whole thing with aluminum foil. Cord Jefferson recalls seeing it in an episode of the old television program Queer Eye for the Straight Guy. But plenty of other people I checked with, like me, had had no idea.
Whatever. I am not claiming to be the Charles Darwin of putting pizza in a skillet, nor the Alfred Russel Wallace. I wish only to be a Thomas Henry Huxley, doing my part to promote a discovery that is true and which has the power to reshape our understanding of the fundamentals of life:
Pizza is best reheated in a skillet.
If you are not already convinced of this, try this thought experiment. Picture a sandwich of cheese between two slices of soft bread. Mentally, butter that bread on the outside and put it in a skillet over medium-ish heat. What happens to the bottom slice of bread, in a few minutes' time? It becomes crispy. What happens to the cheese in the middle? It melts. If you can believe in grilled cheese sandwiches, you are capable of believing in skillet-reheated pizza.
Just put a slice or two of pizza in the skillet, turn on the burner, and wait. How will you know when it's done? Get this: The cheese will start to melt. That's it. Crisp, hot, leftover pizza.
[Image by Jim Cooke]