Preheat a nonstick skillet over medium heat. Generously butter one side of a slice of bread. Place bread butter-side down in the hot skillet; add 1 slice of cheese. Butter a second slice of bread on one side and place butter-side up on top of cheese.

Cook until lightly browned on one side; flip over and continue cooking until cheese is melted. Repeat with remaining 2 slices of bread, butter, and slice of cheese.