Chefs have been telling us for years that you shouldn’t smash your burger patties in the frying pan because you’ll squeeze all the juices out. So then why do the chains Shake Shack and Smashburger do just that? Because when you do it right, the results are delicious. J. Kenji López-Alt developed a technique called the Food Lab’s Ultra-Smashed Cheeseburgers that I’m going to try out. …as Kenji points out in his cookbook opus The Food Lab, if you smash your...