Prep the apples: Wash, core, and slice the apples into 1/4-inch thick wedges or rounds. Keep the peel on for texture and nutrients. Thinner slices cook faster; thicker slices stay juicier.

Toss with lemon: In a bowl, toss the slices with lemon juice. This keeps them from browning and brightens the flavor.

Mix the coating: In a small bowl, stir together melted butter (or oil), brown sugar, cinnamon, vanilla (if using), and a pinch of salt until it forms a loose paste.

Coat the apples: Pour the mixture over the apples and toss until each slice is evenly glazed. If you like them sweeter, sprinkle on a bit more sugar to taste.

Preheat the air fryer: Set to 375°F (190°C) for 3 minutes. A hot basket helps the edges caramelize right away.

Arrange in the basket: Spread the slices in a single layer. It’s okay if they touch slightly, but avoid heavy stacking. Work in batches if needed.

Air fry: Cook for 7–10 minutes, shaking the basket or flipping the slices halfway. They’re done when the edges are lightly browned and the centers are tender.

Finish and serve: Let them cool for 2 minutes to set the glaze. Serve warm as a snack, dessert topping, or alongside yogurt or pancakes.