Who better to ask for the basics on how to make the best grilled cheese than Chef Eric Greenspan?
The Bread. You want your slices to brown evenly, so Eric says not too use the really good, artisanal stuff. But not "shit bread," either.
The Cheese. Place it on both sides! Choose a nice melty Gruyere or Fontina. I personally love good old classic American. If you want that beautiful "cheese pull," use mozzarella or sharp cheddar. Avoid fresh goat cheese, which is too crumbly/dry. Also steer clear of hard, aged cheeses like Parmesan. Although they'll add great flavor, they're not going to stretch the way you want them to.
The Stuffing. Eric isn't against fillings. Greenspan's Grilled Cheese has a whole lot of inspiration - everything from vegetables to spreads to meats. I personally like to keep cheese as the star (no meat) and bypass things that are too rich, like mayonnaise or avocado.
The Butter. For years, I've been impatiently spreading butter on the bread before grilling, which causes the slices to break. Eric shows me you can just throw it into a hot pan to grease it, place the bread/cheese on top, then immediately turn the heat to cook low and slow.
The Pan. Use a nonstick skillet and cover it up to help melt the cheese. You can also add some water around the sandwich to make the middle cook faster, as demonstrated by Eric in the video!