Ingredients :

• Bread — Use slices at least 1 cm thick. Standard sandwich bread works, but an unsweetened brioche or farmhouse bread provides a more interesting texture — the denser crumb absorbs less butter. Avoid ultra-thin sandwich bread: it soaks up the fat and turns soggy even before browning.
• Cheese — Cheddar is the classic for a reason — it melts well, has character, and stretches. But Emmental, a young Comté, or a mix of both work very well. What matters: at least two generous slices. Use only one, and you’re biting into buttery bread with a vague hint of cheese.
• Butter — Softened at room temperature — not melted, not cold. This makes all the difference. Melted butter soaks the crumb and makes it soft. Cold butter tears the bread when you spread it. Softened, it spreads in a thin, even layer that will brown uniformly in the dry heat of the air fryer.