1. At least 2 different cheeses that work well together. 2. Bread shouldn't be too thick (so the cheese can melt). 3. Use butter (on the outside of the bread

1. At least 2 different cheeses that work well together. 2. Bread shouldn't be too thick (so the cheese can melt). 3. Use butter (on the outside of the bread and/or in the pan). The only technique is to manage the temperature - lower temperature for longer time allows the cheese melt. You want melted cheese on the inside without burning the bread and takes a bit of practice. Mythical Kitchen have a good video on it - https://www.youtube.com/watch?v=FuP3GLXxgY0 https://www.youtube.com/watch?v=FuP3GLXxgY0 - Josh does a great job of explaining the important points while also kind of roasting Gordon Ramsey who famously ruined something as basic as grilled cheese in one of his videos.