Preheat your air fryer: Set it to 375°F (190°C) for 2–3 minutes. A hot basket helps the bread crisp quickly.
Butter the bread: Spread a thin, even layer of softened butter or mayo on one side of each slice. These will be the outside surfaces. Keep the edges covered for even browning.
Assemble the sandwich: Place cheese between the unbuttered sides of the bread. Use 2–3 slices, overlapping to cover edge to edge for a complete melt.
Optional upgrades: Add thin extras like tomato or ham, but keep layers light. Too much filling slows melting.
Air fry, side one: Place the sandwich in the basket, buttered side down. Cook for 4–5 minutes. Check at 3 minutes to make sure it’s browning evenly.
Flip carefully: Use a spatula or tongs to flip. Cook 3–4 more minutes, until the top is golden and the cheese is melted.
Adjust if needed: If the bread is crisping faster than the cheese melts, lower to 350°F (175°C) for 1–2 extra minutes.
Rest and slice: Let it sit 1 minute to set the cheese slightly. Slice diagonally or into halves for the classic look.
Serve hot: Enjoy right away for maximum crunch and stretch.