Preheat air fryer to 370°F for 3 minutes to ensure bread crisps immediately.
Spread 1 teaspoon softened butter on one side of each bread slice evenly from edge to edge; buttered side will touch the air fryer basket.
2 slices bread, 1-2 teaspoons butter
Layer 2-3 thin cheese slices on the unbuttered side of one bread slice. Place the second slice on top with buttered side facing out. Press gently to seal.
2 slices bread, 2-3 slices cheese
Place sandwich in air fryer basket with space around all sides. Cook at 370°F for 7 minutes without opening. Check at 6 minutes for doneness and add 1-2 minutes if needed.
Let sandwich rest for 1 minute before cutting. Serve warm.