Preheat your air fryer to 375°F (190°C).
Spread butter on one side of each slice of bread.
Place one slice of bread, buttered side down, in the air fryer basket.
Add the cheese slices on top of the bread in the basket.
Cover with the second slice of bread, buttered side up.
Cook for 4 minutes, then flip the sandwich carefully.
Cook for an additional 4 minutes or until golden brown.
Check for melty cheese; if needed, cook for another minute.
Remove from the air fryer and let it cool for a minute.
Slice the sandwich and serve immediately.