If you don't like your leftovers cold, here's the best way to reheat a slice of leftover pizza: Put your cold pizza on a non-stick pan and cook it for two minutes over medium-low heat (or until the bottom of the slice is crispy). Then, pour two drops of water (less than a teaspoon) into the pan as far from the pizza as you can get. Cover the pan with a lid and turn the heat to low. Cook it for another minute. What you get is a slice that tastes like it came right out of a fresh pizza.