Spread butter evenly on one side of each slice of bread.
Place two slices of bread, buttered side down, on the skillet. Top each with two slices of cheese, then place the remaining bread slices on top, buttered side up.
Cook for 3–4 minutes on each side, or until the bread is golden brown and the cheese has melted.
Remove from skillet, slice in half if desired, and serve hot.
Notes
For extra flavor, add a slice of tomato or crispy bacon before grilling.
Use a mix of cheeses like cheddar, mozzarella, and Swiss for more depth.
Cooking on low heat ensures the cheese melts before the bread burns.