To achieve a perfectly melted cheese without burning the bread in your grilled cheese sandwich, follow these simple steps. Start by using medium-low heat on your skillet or griddle. If you find that the cheese isn't melting as quickly as you'd like, you can cover the skillet with a lid or a heat-safe plate to create a mini-oven effect, helping the cheese melt faster. It's essential to use thinly sliced cheese, as it melts more easily than thicker slices. Make sure your skillet or griddle is preheated before adding the sandwich, ensuring that the cheese starts melting as soon as the bread touches the hot surface. Apply butter generously to the outer sides of the bread slices, as the butter acts as a protective layer, preventing the bread from burning while allowing it to develop a golden-brown, crispy texture. Be patient and flip the sandwich occasionally to ensure even cooking.